win32file.CreateIoCompletionPort
PyHANDLE = CreateIoCompletionPort(handle, existing , completionKey , numThreads )
Can associate an instance of an opened file with a newly created or an existing input/output (I/O) completion port; or it can create an I/O completion port without associating it with a file.
Parameters
Return Value
If an existing handle to a completion port is passed, the result of this function will be that same handle. See MSDN for more details.