function a 
{
   b {
        write-host 'hello'
   }
}

function b 
{
   param([scriptblock]$sb)
   &$sb
}

function a 
{
   b 
  {
        write-host 'hello'
   }
}

function b 
{
   param([scriptblock]$sb)
   &$sb
}

PS C:\> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      6.0.0-rc.2
PSEdition                      Core
GitCommitId                    v6.0.0-rc.2
OS                             Microsoft Windows 6.3.9600
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0