def _set_expiration_date_time(self, v, load=False):
    """
    Setter method for expiration_date_time, mapped from YANG variable /macsec/mka/key_chains/key_chain/mka_keys/mka_key/state/expiration_date_time (union)
    If this variable is read-only (config: false) in the
    source YANG file, then _set_expiration_date_time is considered as a private
    method. Backends looking to populate this variable should
    do so via calling thisObj._set_expiration_date_time() directly.

    YANG Description: Key date and time expiration according to local date and time