def __repr__(self):
        #s= "(type : {}".format(self.type)
        s = ""
        if self.type == 0:
            s += "(I:{})".format(self.sub1)
        if self.type == 1:
            s += "1-{}".format(repr(self.sub1))
        if self.type == 2:
            s += "({} | {})".format(repr(self.sub1), repr(self.sub2))
        return s