# 1
importjson
# 2
dict_a={}
dict_b=dict()
# 3
dict_a={"a1":"b1","a2":"b2","a3":"b3"}
# 4
ks=dict_a.keys()
print(type(ks))
# 5
vs=dict_a.values()
print(type(vs))
# 6
print(dict_a.items())
# 7
dict_a["a1"] ="b3"
dict_a["a3"] ="b1"
# 8
print(dict_a)
# 9
dict_a.pop("a1")
# 10
print(dict_a)
# 11
dict_b.update(dict_a)
# 12
print(dict_b)
# 13
a1=dict_b.get('a1')
print(a1)
# 14
dict_b["a1"] =a1
# 15
dict_b["a4"] ='null'
# 16
print(dict_b)
print(type(dict_b))
# 17
json_c=json.dumps(dict_b)
# 18 None --> null None为python特有的数据类型
print(json_c)
print(type(json_c))
# 19
dict_c=json.loads(json_c)
print(dict_b)
