dict class override: how access parent values?

[Andrey]

I'm try override dict class for way that compatible with standart dict class. How i can get access to parent dict attribute if i override getitem method?

class CSJSON(dict):
    def __getitem__(self, Key : str):
       Key = Key + 'zzz' # sample of key modification for app use
       return(super()[Key])

Then i faced error:

Error:
'super' object is not subscriptable.

If i'm use self[Key] - then i get infinite recursive call of getitem.

[deanhystad]

class CSJSON(dict):
    def __setitem__(self, key : str, value : all):
       return super().__setitem__(key+'zzz', value)

    def __getitem__(self, key : str):
       return super().__getitem__(key+'zzz')

x = CSJSON()
x['Hi'] = "Hola"
x['Bye'] = 'Adios'
print(*x.keys(), x['Hi'])

Output:
Hizzz Byezzz Hola