python中一些有意思的东西

a=3;b=3
print a is b   #True
print a+3 is b+3      #True
print a+300 is b+300  #False

print type([]) #
print type(()) #
print type(([]))      #
print type(([(())]))  #

c = d = 4; c *= 4
print c is d   #False
e = f = [4]; e *= 4
print e is f   #True

print type({():()})   #
print type({[]:[]})   #TypeError: unhashable type: 'list'