@staticmethod
def model_version():
    """Return current version of this model, counting up from 0.

        Models may not be backwards-compatible with older versions.
        Version 1 split from version 0 on Aug 29, 2018.
        To use version 0, use --model legacy:seq2seq:0
        (legacy agent code is located in parlai/agents/legacy_agents).
        """
    return 1
