def add(a, b):
return a + b
def sub(a, b):
return a - b
def demo_dict():
dicta={4:16,1:1,2:4,3:9}
# dicta = {4: 16, 1: 1, 2: 4, 3: 9}
print (1,dicta)
print (2,dicta.keys(), dicta.values())
print (3, 1 in dicta, '3' in dicta)
for key, value in dicta.items():
print (key, value)
dictb = {'+': add, '-': sub}
print (4, dictb['+'](1, 2))
print (5, dictb.get('-')(15, 3))
dictb['*'] = 'x'
print (dictb)
dicta.pop(4)
print (6, dicta)
del dicta[1]
print (7,dicta)
if __name__ == '__main__':
demo_dict()