Returns a String comprised of the XdmValue.AsString() value of each item in the sequence with the given separator string between each. If the sequence is empty (Empty is true) then the empty string is returned.
[Visual Basic] Function AsString( _    ByVal separator As String _ ) As String
A separator string, such as "\n", to be inserted between the XdmValue.asString value of each item in the sequence. A value of null is equivalent to the empty string which causes all items to be concatenated with no separator.