def METHOD_NAME(self):
    """
    GnomeOIl needs to be hashable, so that is can be used with lru_cache
    This only tests that the SAME oil object is hashable and recoverable,
    but that's OK for caching.
    NOTE: This doesn't test at all whether the hash "works"
          e.g. that two different GnomeOils don't hash the same
          That may be OK -- as equality works, yes?
    """
    oil1 = GnomeOil('oil_ans_mp')
    # can I put it in a dict, and get it out again?
    d = {}
    d[oil1] = "yes"
    assert d[oil1] == "yes"