metadata.py 文件源码

def write_metadata(self, **metadata):
        # type: (**Any) -> Optional[int]
        """Writes metadata to the output stream if output is not suppressed.

        :param **metadata: JSON-serializeable metadata kwargs to write
        """
        if self.suppress_output:
            return 0  # wrote 0 bytes

        metadata_line = json.dumps(metadata, sort_keys=True) + os.linesep
        metadata_output = ''  # type: Union[str, bytes]
        if 'b' in self._output_mode:
            metadata_output = metadata_line.encode('utf-8')
        else:
            metadata_output = metadata_line
        return self._output_stream.write(metadata_output)