def stab(f1, m1):
    """Return 1.5 if the move's type is one of the user's types,
    otherwise return 0, unless the user's ability is Adaptibility,
    in which case return 2.
    """
    if m1.type in f1.types:
        return 2 if f1.ability == 91 else 1.5

    else:
        return 1