建立一个时间类time，它包含huor，minute，second的实例属性

（1）设计时间显示函数show(self)
(2)设计两个时间大小比较函数compare（self，t），其中t是另外一个时间。

# -*- coding: UTF-8 -*-

class time(object):
    def __init__(self, h=0, m=0, s=0):
        self.hour = h
        self.minute = m
        self.second = s
    def compare(self, t):
        if (self.hour == t.hour):
            if (self.minute == t.minute):
                if (self.second == t.second):
                    return 0
                else:
                    return self.second - t.second
            else:
                return self.minute - t.minute
        else:
            return self.hour - t.hour

def cmp2str(n):
    if (n == 0):
        return "="
    elif (n < 0):
        return "<"
    else:
        return ">"

t1 = time(2019, 3, 1)
t2 = time(2019, 3, 20)
t3 = time(2019, 5, 1)
t4 = time(2019, 5, 1)
print(cmp2str(t1.compare(t2)))
print(cmp2str(t2.compare(t3)))
print(cmp2str(t3.compare(t4)))
print(cmp2str(t4.compare(t1)))

<
<
=
>