How to change the number into the same expression's string and vice versa?

[contro opinion]

In the python3 console:

    >>> a=18
    >>> b='18'
    >>> str(a) == b
    True
    >>> int(b) == a
    True


Now how to change a1,a2,a3  into b1,b2,b3 and vice versa?
a1=0xf4
a2=0o36
a3=011

b1='0xf4'
b2='0o36'
b3='011'

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