VB 支持对元组赋值吗？如果是的话，语法是什么？
Private Function GetPeStream(metadataDiagnostics As DiagnosticBag, peStreamProvider As EmitStreamProvider, metadataOnly As Boolean) As (peStream As Stream, signingStream As Stream, selectedStream As Stream)
Return ...
End Function
Dim ret As Stream
Dim peStream as Stream
Dim signingInputStream as Stream
(peStream, signingInputStream, ret) = GetPeStream(metadataDiagnostics, peStreamProvider, metadataOnly)