package and import ( "io" ) type ReadCloser struct { io.Reader CloseFunc func() error } var _ io.ReadCloser = (*ReadCloser)(nil) // Close implements io.ReadCloser func (rac *ReadCloser) Close() error { return rac.CloseFunc() } // WriteCloser implements io.WriteCloser by reading from a particular io.Writer // and then calling the provided "Close()" method. type WriteCloser struct { io.Writer CloseFunc func() error } var _ io.WriteCloser = (*WriteCloser)(nil) // Close implements io.WriteCloser func (wac *WriteCloser) Close() error { return wac.CloseFunc() }