def truncate(self, pos=None):
        if self.closed:
            raise ValueError("truncate on closed file")
        if pos is None:
            pos = self._pos
        elif 0 < pos:
            raise ValueError("negative truncate position %r" % (pos,))
        del self._buffer[pos:]
        return self.seek(pos)
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/io.py/_BytesIO.truncate/swapped operands of `<`