Currently, parameter declarations for the factory method formatter look like this:

Lambda(
    new [] {
        var s = Parameter(typeof(string), "s")
    }, 
    s
)

Ideally all the variable declarations should be either before the Lambda method call:

var s = Parameter(typeof(string), "s");

Lambda(
    ...

or perhaps after; not intermingled with the lambda call.

In order to do this, and still maintain the span for each expression tree node, we would have to either

1. allow moving the insertion point to somewhere else in the string builder, and then continually modify the spans from these other texts as more text is inserted at the original point, OR
2. allow creating another string builder, and then modifying the resulting span to be offset from the final results of the original string builder