How to use the jplephem.pck.PCK function in jplephem

def read_binary(self, file):
        """Read binary segments descriptions from a DAF/PCK file.

        Binary segments live in ``.bpc`` files and predict how a body
        like a planet or moon will be oriented on a given date.

        """
        file.seek(0)
        if file.read(7) != b'DAF/PCK':
            raise ValueError('file must start with the bytes "DAF/PCK"')
        pck = PCK(DAF(file))
        self._binary_files.append(pck)
        for segment in pck.segments:
            self._segment_map[segment.body] = segment