Return a tuple containing the C-struct fields in this stream
        specified by *template* and starting at *offset*.

def read_fields(self, template, offset=0):
        """
        Return a tuple containing the C-struct fields in this stream
        specified by *template* and starting at *offset*.
        """
        self._file.seek(offset)
        bufr = self._file.read(calcsize(template))
        return unpack_from(template, bufr)