def METHOD_NAME(self, pos, whence=0):
    """
    Resets stream to the beginning.
    :param int pos: only allowed value is ``0``
    :param int whence: only allowed value is ``0``
    """
    if pos != 0 or whence != 0:
        raise io.UnsupportedOperation('Chained stream can only be seeked to beginning')
    self._reset_chain()
    return self.tell()