#1

importjson

#2

dict_a={}

dict_b={}

#3

dict_a['a1']='b1'

dict_a['a2']='b2'

dict_a['a3']='b3'

#4

ks=dict_a.keys()

print(ks)

print(type(ks))

#5, 6

vs=dict_a.values()

print(vs)

print(dict_a.items())

#7 8

dict_a['a1']='b3'

dict_a['a3']='b1'

print(dict_a)

#9 10

dict_a.pop('a1')

print(dict_a)

#11

dict_b.update(dict_a)

#12 13 14

print(dict_b)

a1=dict_b.get('a1')

print(a1)

#15 16

dict_b['a1']=a1

dict_b['a4']='null'

print(dict_b)

print(type(dict_b))

#17 18

json_c ="""

[

{

"dict_b": {

"a2": "b2",

"a3": "b1",

"a1": None,

"a4": "null"

}

}

]

"""

print(json_c)

print(type(json_c))

#19

json_c=json.dumps(json_c)

dict_c=json.loads(json_c)

print(dict_c)

print(type(dict_c))