code: def __get_table_size(self):
  		
  		length = ctypes.wintypes.DWORD()
  		res = self.method(None, length, False)
  		if res != errors.ERROR_INSUFFICIENT_BUFFER:
  			raise RuntimeError("Error getting table length (%d)" % res)
  		return length.value
docs: Retrieve the size of the buffer needed by calling the method
  		with a null pointer and length of zero. This should trigger an
  		insufficient buffer error and return the size needed for the
  		buffer.