pythonlearn/html-009/book005.html at master · StudyCourse/pythonlearn

History

520 lines (507 loc) · 36.8 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

<!DOCTYPE html>

<html>

<head>

<title>Functions</title>

</head>

<body>

<hr />

<h1 class="chapter" id="sec45">Chapter&#XA0;4&#XA0;&#XA0;Functions</h1>

<h2 class="section" id="sec46">4.1&#XA0;&#XA0;Function calls</h2>

<a id="hevea_default191"></a>In the context of programming, a function is a named sequence of

statements that performs a computation. When you define a function,

you specify the name and the sequence of statements. Later, you can

&#X201C;call&#X201D; the function by name.

We have already seen one example of a function call:<pre class="verbatim">>>> type(32)

</pre>The name of the function is type. The expression in parentheses

is called the argument of the function. The argument is

a value or variable that we are passing into the function as input

to the function.

The result, for the type function, is the type of the argument.<a id="hevea_default192"></a>It is common to say that a function &#X201C;takes&#X201D; an argument and &#X201C;returns&#X201D;

a result. The result is called the return value.<a id="hevea_default193"></a>

<h2 class="section" id="sec47">4.2&#XA0;&#XA0;Built-in functions</h2>

Python provides a number of important built-in functions that

we can use without needing to provide the function definition.

The creators of Python wrote a set of functions

to solve common problems and included them in Python for us to use.The max and min functions give us the largest and

smallest values in a list, respectively:<pre class="verbatim">>>> max('Hello world')

'w'

>>> min('Hello world')

' '

>>>

</pre>The max function tells us the &#X201C;largest character&#X201D; in the

string (which turns out to be the letter &#X201C;w&#X201D;) and the min

function shows us the smallest character which turns out to be a

space.Another very common built-in function is the len function

which tells us how many items are in its argument. If the argument

to len is a string, it returns the number of characters

in the string.<pre class="verbatim">>>> len('Hello world')

>>>

</pre>These functions are not limited to looking at strings, they can operate

on any set of values as we will see in later chapters.You should treat the names of built-in functions as reserved words (i.e.

avoid using &#X201C;max&#X201D; as a variable name).

<h2 class="section" id="sec48">4.3&#XA0;&#XA0;Type conversion functions</h2>

<a id="hevea_default196"></a>Python also provides built-in functions that convert values

from one type to another. The int function takes any value and

converts it to an integer, if it can, or complains otherwise:<a id="hevea_default197"></a>

<a id="hevea_default198"></a><pre class="verbatim">>>> int('32')

>>> int('Hello')

ValueError: invalid literal for int(): Hello

</pre>int can convert floating-point values to integers, but it

doesn&#X2019;t round off; it chops off the fraction part:<pre class="verbatim">>>> int(3.99999)

>>> int(-2.3)

-2

</pre>float converts integers and strings to floating-point

numbers:<a id="hevea_default199"></a>

<a id="hevea_default200"></a><pre class="verbatim">>>> float(32)

32.0

>>> float('3.14159')

3.14159

</pre>Finally, str converts its argument to a string:<a id="hevea_default201"></a>

<a id="hevea_default202"></a><pre class="verbatim">>>> str(32)

'32'

>>> str(3.14159)

'3.14159'

</pre>

<h2 class="section" id="sec49">4.4&#XA0;&#XA0;Random numbers</h2>

<a id="hevea_default206"></a>Given the same inputs, most computer programs generate the same

outputs every time, so they are said to be deterministic.

Determinism is usually a good thing, since we expect the same

calculation to yield the same result. For some applications, though,

we want the computer to be unpredictable. Games are an obvious

example, but there are more.Making a program truly nondeterministic turns out to be not so easy,

but there are ways to make it at least seem nondeterministic. One of

them is to use algorithms that generate pseudorandom numbers.

Pseudorandom numbers are not truly random because they are generated

by a deterministic computation, but just by looking at the numbers it

is all but impossible to distinguish them from random.<a id="hevea_default207"></a>

<a id="hevea_default208"></a>The random module provides functions that generate

pseudorandom numbers (which I will simply call &#X201C;random&#X201D; from

here on).<a id="hevea_default209"></a>

<a id="hevea_default210"></a>The function random returns a random float

between 0.0 and 1.0 (including 0.0 but not 1.0). Each time you

call random, you get the next number in a long series. To see a

sample, run this loop:<pre class="verbatim">import random

for i in range(10):

x = random.random()

print x

</pre>This program produces the following list of 10 random numbers

between 0.0 and up to but not including 1.0.<pre class="verbatim">0.301927091705

0.513787075867

0.319470430881

0.285145917252

0.839069045123

0.322027080731

0.550722110248

0.366591677812

0.396981483964

0.838116437404

</pre><div class="theorem">Exercise&#XA0;1&#XA0;&#XA0;

Run the program on your system and see what numbers you get.

Run the program more than once and see what numbers you get.

</div>The random function is only one of many

functions which handle random numbers.

The function randint takes parameters low and

high and returns an integer between low and

high (including both).<a id="hevea_default211"></a>

<a id="hevea_default212"></a><pre class="verbatim">>>> random.randint(5, 10)

>>> random.randint(5, 10)

</pre>To choose an element from a sequence at random, you can use

choice:<a id="hevea_default213"></a>

<a id="hevea_default214"></a><pre class="verbatim">>>> t = [1, 2, 3]

>>> random.choice(t)

</pre>The random module also provides functions to generate

random values from continuous distributions including

Gaussian, exponential, gamma, and a few more.

<h2 class="section" id="sec50">4.5&#XA0;&#XA0;Math functions</h2>

<a id="hevea_default218"></a>Python has a math module that provides most of the familiar

mathematical functions.

Before we can use the module, we have to import it:<pre class="verbatim">>>> import math

</pre>This statement creates a module object named math. If

you print the module object, you get some information about it:<pre class="verbatim">>>> print math

</pre>The module object contains the functions and variables defined in the

module. To access one of the functions, you have to specify the name

of the module and the name of the function, separated by a dot (also

known as a period). This format is called dot notation.<a id="hevea_default219"></a><pre class="verbatim">>>> ratio = signal_power / noise_power

>>> decibels = 10 * math.log10(ratio)

>>> radians = 0.7

>>> height = math.sin(radians)

</pre>The first example computes the logarithm base 10 of the

signal-to-noise ratio. The math module also provides a

function called log that computes logarithms base e.<a id="hevea_default220"></a>

<a id="hevea_default225"></a>The second example finds the sine of radians. The name of the

variable is a hint that sin and the other trigonometric

functions (cos, tan, etc.) take arguments in radians. To

convert from degrees to radians, divide by 360 and multiply by 2

&#X3C0;:<pre class="verbatim">>>> degrees = 45

>>> radians = degrees / 360.0 * 2 * math.pi

>>> math.sin(radians)

0.707106781187

</pre>The expression math.pi gets the variable pi from the math

module. The value of this variable is an approximation

of &#X3C0;, accurate to about 15 digits.<a id="hevea_default226"></a>If you know

your trigonometry, you can check the previous result by comparing it to

the square root of two divided by two:<a id="hevea_default227"></a>

<a id="hevea_default228"></a><pre class="verbatim">>>> math.sqrt(2) / 2.0

0.707106781187

</pre>

<h2 class="section" id="sec51">4.6&#XA0;&#XA0;Adding new functions</h2>

So far, we have only been using the functions that come with Python,

but it is also possible to add new functions.

A function definition specifies the name of a new function and

the sequence of statements that execute when the function is called.

Once we define a function, we can reuse the function over and over

throughout our program.<a id="hevea_default229"></a>

<a id="hevea_default231"></a>Here is an example:<pre class="verbatim">def print_lyrics():

print "I'm a lumberjack, and I'm okay."

print 'I sleep all night and I work all day.'

</pre>def is a keyword that indicates that this is a function

definition. The name of the function is <code>print_lyrics</code>. The

rules for function names are the same as for variable names: letters,

numbers and some punctuation marks are legal, but the first character

can&#X2019;t be a number. You can&#X2019;t use a keyword as the name of a function,

and you should avoid having a variable and a function with the same

name.<a id="hevea_default232"></a>

<a id="hevea_default234"></a>The empty parentheses after the name indicate that this function

doesn&#X2019;t take any arguments. Later we will build functions that

take arguments as their inputs.<a id="hevea_default235"></a>

<a id="hevea_default239"></a>The first line of the function definition is called the header;

the rest is called the body. The header has to end with a colon

and the body has to be indented. By convention, the indentation is

always four spaces. The body can contain

any number of statements.The strings in the print statements are enclosed in double

quotes. Single quotes and double quotes do the same thing;

most people use single quotes except in cases like this where

a single quote (which is also an apostrophe) appears in the string.<a id="hevea_default240"></a>If you type a function definition in interactive mode, the interpreter

prints ellipses (...) to let you know that the definition

isn&#X2019;t complete:<pre class="verbatim">>>> def print_lyrics():

... print "I'm a lumberjack, and I'm okay."

... print 'I sleep all night and I work all day.'

...

</pre>To end the function, you have to enter an empty line (this is

not necessary in a script).Defining a function creates a variable with the same name.<pre class="verbatim">>>> print print_lyrics

>>> print type(print_lyrics)

</pre>The value of <code>print_lyrics</code> is a function object, which

has type <code>'function'</code>.<a id="hevea_default241"></a>

<a id="hevea_default242"></a>The syntax for calling the new function is the same as

for built-in functions:<pre class="verbatim">>>> print_lyrics()

I'm a lumberjack, and I'm okay.

I sleep all night and I work all day.

</pre>Once you have defined a function, you can use it inside another

function. For example, to repeat the previous refrain, we could write

a function called <code>repeat_lyrics</code>:<pre class="verbatim">def repeat_lyrics():

print_lyrics()

</pre>And then call <code>repeat_lyrics</code>:<pre class="verbatim">>>> repeat_lyrics()

I'm a lumberjack, and I'm okay.

I sleep all night and I work all day.

I'm a lumberjack, and I'm okay.

I sleep all night and I work all day.

</pre>But that&#X2019;s not really how the song goes.

<h2 class="section" id="sec52">4.7&#XA0;&#XA0;Definitions and uses</h2>

<a id="hevea_default243"></a>Pulling together the code fragments from the previous section, the

whole program looks like this:<pre class="verbatim">def print_lyrics():

print "I'm a lumberjack, and I'm okay."

print 'I sleep all night and I work all day.'

def repeat_lyrics():

print_lyrics()

repeat_lyrics()

</pre>This program contains two function definitions: <code>print_lyrics</code> and

<code>repeat_lyrics</code>. Function definitions get executed just like other

statements, but the effect is to create function objects. The statements

inside the function do not get executed until the function is called, and

the function definition generates no output.<a id="hevea_default244"></a>As you might expect, you have to create a function before you can

execute it. In other words, the function definition has to be

executed before the first time it is called.<div class="theorem">Exercise&#XA0;2&#XA0;&#XA0;

Move the last line of this program

to the top, so the function call appears before the definitions. Run

the program and see what error

message you get.

</div><div class="theorem">Exercise&#XA0;3&#XA0;&#XA0;

Move the function call back to the bottom

and move the definition of <code>print_lyrics</code> after the definition of

<code>repeat_lyrics</code>. What happens when you run this program?

</div>

<h2 class="section" id="sec53">4.8&#XA0;&#XA0;Flow of execution</h2>

<a id="hevea_default245"></a>In order to ensure that a function is defined before its first use,

you have to know the order in which statements are executed, which is

called the flow of execution.Execution always begins at the first statement of the program.

Statements are executed one at a time, in order from top to bottom.Function definitions do not alter the flow of execution of the

program, but remember that statements inside the function are not

executed until the function is called.A function call is like a detour in the flow of execution. Instead of

going to the next statement, the flow jumps to the body of

the function, executes all the statements there, and then comes back

to pick up where it left off.That sounds simple enough, until you remember that one function can

call another. While in the middle of one function, the program might

have to execute the statements in another function. But while

executing that new function, the program might have to execute yet

another function!Fortunately, Python is good at keeping track of where it is, so each

time a function completes, the program picks up where it left off in

the function that called it. When it gets to the end of the program,

it terminates.What&#X2019;s the moral of this sordid tale? When you read a program, you

don&#X2019;t always want to read from top to bottom. Sometimes it makes

more sense if you follow the flow of execution.

<h2 class="section" id="sec54">4.9&#XA0;&#XA0;Parameters and arguments</h2>

<a id="hevea_default249"></a>Some of the built-in functions we have seen require arguments. For

example, when you call math.sin you pass a number

as an argument. Some functions take more than one argument:

math.pow takes two, the base and the exponent.Inside the function, the arguments are assigned to

variables called parameters. Here is an example of a

user-defined function that takes an argument:<a id="hevea_default250"></a><pre class="verbatim">def print_twice(bruce):

print bruce

</pre>This function assigns the argument to a parameter

named bruce. When the function is called, it prints the value of

the parameter (whatever it is) twice.This function works with any value that can be printed.<pre class="verbatim">>>> print_twice('Spam')

Spam

>>> print_twice(17)

>>> print_twice(math.pi)

3.14159265359

</pre>The same rules of composition that apply to built-in functions also

apply to user-defined functions, so we can use any kind of expression

as an argument for <code>print_twice</code>:<a id="hevea_default251"></a><pre class="verbatim">>>> print_twice('Spam '*4)

Spam Spam Spam Spam

>>> print_twice(math.cos(math.pi))

-1.0

</pre>The argument is evaluated before the function is called, so

in the examples the expressions <code>'Spam '*4</code> and

math.cos(math.pi) are only evaluated once.<a id="hevea_default252"></a>You can also use a variable as an argument:<pre class="verbatim">>>> michael = 'Eric, the half a bee.'

>>> print_twice(michael)

Eric, the half a bee.

</pre>The name of the variable we pass as an argument (michael) has

nothing to do with the name of the parameter (bruce). It

doesn&#X2019;t matter what the value was called back home (in the caller);

here in <code>print_twice</code>, we call everybody bruce.

<h2 class="section" id="sec55">4.10&#XA0;&#XA0;Fruitful functions and void functions</h2>

<a id="hevea_default256"></a> Some of the functions we are using, such as the math functions, yield

results; for lack of a better name, I call them fruitful

functions. Other functions, like <code>print_twice</code>, perform an

action but don&#X2019;t return a value. They are called void

functions.When you call a fruitful function, you almost always

want to do something with the result; for example, you might

assign it to a variable or use it as part of an expression:<pre class="verbatim">x = math.cos(radians)

golden = (math.sqrt(5) + 1) / 2

</pre>When you call a function in interactive mode, Python displays

the result:<pre class="verbatim">>>> math.sqrt(5)

2.2360679774997898

</pre>But in a script, if you call a fruitful function and do

not store the result of the function in a variable,

the return value vanishes into the mist!<pre class="verbatim">math.sqrt(5)

</pre>This script computes the square root of 5, but since it doesn&#X2019;t store

the result in a variable or display the result, it is not very useful.<a id="hevea_default257"></a>

<a id="hevea_default258"></a>Void functions might display something on the screen or have some

other effect, but they don&#X2019;t have a return value. If you try to

assign the result to a variable, you get a special value called

None.<a id="hevea_default259"></a>

<a id="hevea_default260"></a><pre class="verbatim">>>> result = print_twice('Bing')

Bing

>>> print result

None

</pre>The value None is not the same as the string <code>'None'</code>.

It is a special value that has its own type:<pre class="verbatim">>>> print type(None)

</pre>To return a result from a function, we use the return statement

in our function. For example, we could make a very

simple function called addtwo

that adds two numbers together and return a result.<pre class="verbatim">def addtwo(a, b):

added = a + b

return added

x = addtwo(3, 5)

print x

</pre>When this script executes, the print statement will print out &#X201C;8&#X201D;

because the addtwo function was called with 3 and 5 as arguments.

Within the function the parameters a and b were 3 and 5

respectively. The function computed the sum of the two numbers and placed

it in the local function variable named added

and used the return statement

to send the computed value back to the calling code

as the function result which was assigned

to the variable x and printed out.

<h2 class="section" id="sec56">4.11&#XA0;&#XA0;Why functions?</h2>

<a id="hevea_default261"></a>It may not be clear why it is worth the trouble to divide

a program into functions. There are several reasons:<ul class="itemize"><li class="li-itemize">Creating a new function gives you an opportunity to name a group

of statements, which makes your program easier to read, understand

and debug.</li><li class="li-itemize">Functions can make a program smaller by eliminating repetitive

code. Later, if you make a change, you only have

to make it in one place.</li><li class="li-itemize">Dividing a long program into functions allows you to debug the

parts one at a time and then assemble them into a working whole.</li><li class="li-itemize">Well-designed functions are often useful for many programs.

Once you write and debug one, you can reuse it.</li></ul>Throughout the rest of the book, often we will use a function definition to

explain a concept. Part of the skill of creating and using functions is

to have a function properly capture an idea such as &#X201C;find the smallest

value in a list of values&#X201D;. Later we will show you code that finds

the smallest in a list of values and we will present it to you as a function

named min which takes a list of values as its argument and

returns the smallest value in the list.

<h2 class="section" id="sec57">4.12&#XA0;&#XA0;Debugging</h2>

<a id="hevea_default262"></a>If you are using a text editor to write your scripts, you might

run into problems with spaces and tabs. The best way to avoid

these problems is to use spaces exclusively (no tabs). Most text

editors that know about Python do this by default, but some

don&#X2019;t.<a id="hevea_default263"></a>Tabs and spaces are usually invisible, which makes them

hard to debug, so try to find an editor that manages indentation

for you.Also, don&#X2019;t forget to save your program before you run it. Some

development environments do this automatically, but some don&#X2019;t.

In that case the program you are looking at in the text editor

is not the same as the program you are running.Debugging can take a long time if you keep running the same,

incorrect, program over and over!Make sure that the code you are looking at is the code you are running.

If you&#X2019;re not sure, put something like <code>print 'hello'</code> at the

beginning of the program and run it again. If you don&#X2019;t see

<code>hello</code>, you&#X2019;re not running the right program!

<h2 class="section" id="sec58">4.13&#XA0;&#XA0;Glossary</h2>

<dl class="description"><dt class="dt-description">algorithm:</dt><dd class="dd-description"> A general process for solving a category of

problems.

<a id="hevea_default264"></a></dd><dt class="dt-description">argument:</dt><dd class="dd-description"> A value provided to a function when the function is called.

This value is assigned to the corresponding parameter in the function.

<a id="hevea_default265"></a></dd><dt class="dt-description">body:</dt><dd class="dd-description"> The sequence of statements inside a function definition.

<a id="hevea_default266"></a></dd><dt class="dt-description">composition:</dt><dd class="dd-description"> Using an expression as part of a larger expression,

or a statement as part of a larger statement.

<a id="hevea_default267"></a></dd><dt class="dt-description">deterministic:</dt><dd class="dd-description"> Pertaining to a program that does the same

thing each time it runs, given the same inputs.

<a id="hevea_default268"></a></dd><dt class="dt-description">dot notation:</dt><dd class="dd-description"> The syntax for calling a function in another

module by specifying the module name followed by a dot (period) and

the function name.

<a id="hevea_default269"></a></dd><dt class="dt-description">flow of execution:</dt><dd class="dd-description"> The order in which statements are executed during

a program run.

<a id="hevea_default270"></a></dd><dt class="dt-description">fruitful function:</dt><dd class="dd-description"> A function that returns a value.

<a id="hevea_default271"></a></dd><dt class="dt-description">function:</dt><dd class="dd-description"> A named sequence of statements that performs some

useful operation. Functions may or may not take arguments and may or

may not produce a result.

<a id="hevea_default272"></a></dd><dt class="dt-description">function call:</dt><dd class="dd-description"> A statement that executes a function. It

consists of the function name followed by an argument list.

<a id="hevea_default273"></a></dd><dt class="dt-description">function definition:</dt><dd class="dd-description"> A statement that creates a new function,

specifying its name, parameters, and the statements it executes.

<a id="hevea_default274"></a></dd><dt class="dt-description">function object:</dt><dd class="dd-description"> A value created by a function definition.

The name of the function is a variable that refers to a function

object.

<a id="hevea_default275"></a></dd><dt class="dt-description">header:</dt><dd class="dd-description"> The first line of a function definition.

<a id="hevea_default276"></a></dd><dt class="dt-description">import statement:</dt><dd class="dd-description"> A statement that reads a module file and creates

a module object.

<a id="hevea_default278"></a></dd><dt class="dt-description">module object:</dt><dd class="dd-description"> A value created by an import statement

that provides access to the data and code defined in a module.

<a id="hevea_default279"></a></dd><dt class="dt-description">parameter:</dt><dd class="dd-description"> A name used inside a function to refer to the value

passed as an argument.

<a id="hevea_default280"></a></dd><dt class="dt-description">pseudorandom:</dt><dd class="dd-description"> Pertaining to a sequence of numbers that appear

to be random, but are generated by a deterministic program.

<a id="hevea_default281"></a></dd><dt class="dt-description">return value:</dt><dd class="dd-description"> The result of a function. If a function call

is used as an expression, the return value is the value of

the expression.

<a id="hevea_default282"></a></dd><dt class="dt-description">void function:</dt><dd class="dd-description"> A function that doesn&#X2019;t return a value.

<h2 class="section" id="sec59">4.14&#XA0;&#XA0;Exercises</h2>

<div class="theorem">Exercise&#XA0;4&#XA0;&#XA0;

What is the purpose of the "def" keyword in Python?a) It is slang that means "the following code is really cool"

b) It indicates the start of a function

c) It indicates that the following indented section of code is to be stored for later

d) b and c are both true

e) None of the above

</div><div class="theorem">Exercise&#XA0;5&#XA0;&#XA0;

What will the following Python program print out?<pre class="verbatim">def fred():

print "Zap"

def jane():

print "ABC"

jane()

fred()

jane()

</pre>a) Zap ABC jane fred jane

b) Zap ABC Zap

c) ABC Zap jane

d) ABC Zap ABC

e) Zap Zap Zap

</div><div class="theorem">Exercise&#XA0;6&#XA0;&#XA0;

Rewrite your pay computation with time-and-a-half for overtime

and create a function called computepay which takes

two parameters (hours and rate).<pre class="verbatim">Enter Hours: 45

Enter Rate: 10

Pay: 475.0

</pre></div><div class="theorem">Exercise&#XA0;7&#XA0;&#XA0;

Rewrite the grade program from the previous chapter

using a function called computegrade that takes

a score as its parameter and returns a grade as a string.<pre class="verbatim">Score Grade

> 0.9 A

> 0.8 B

> 0.7 C

> 0.6 D

<= 0.6 F

Program Execution:

Enter score: 0.95

Enter score: perfect

Bad score

Enter score: 10.0

Bad score

Enter score: 0.75

Enter score: 0.5

</pre>Run the program repeatedly to test the various different values

for input.

</div>

<hr />

</body>

</html>

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

FilesExpand file tree

book005.html

Latest commit

History

book005.html

File metadata and controls