assert 断言

assert

通常用法是：

assert condition

用来让程序测试这个condition，若是condition为False则抛出一个AssertionError，逻辑上等同于

if not condition:
    raise AssertionError()

好比下面的例子

>>> assert 1==1
>>> assert 1==0
Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    assert 1==0
AssertionError
>>> assert True
>>> assert False
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    assert False
AssertionError
>>> assert 3<2
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    assert 3<2
AssertionError