'Tests for equality.
Is currently weak; needs stronger comparison testing'

def __eq__(self, other):

    if (other == 0):
        other = Dyadic(0)
    other = _check_dyadic(other)
    if ((self.args == []) and (other.args == [])):
        return True
    elif ((self.args == []) or (other.args == [])):
        return False
    return (set(self.args) == set(other.args))
