Take a look at advanced functions: http://technet.microsoft.com/en-us/library/hh847743.aspx
Param ( [parameter(Mandatory=$true)] [ValidateNotNull()] $x )
Take a look at advanced functions: http://technet.microsoft.com/en-us/library/hh847743.aspx
Param ( [parameter(Mandatory=$true)] [ValidateNotNull()] $x )