Quick questions about Python Dictionary

def card_conv(x: int, r: int) -> str:
    """Returns a string representing the number after converting an integer x to r"""

    d = '' # string after conversion
    dchar = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    n = len(str(x)) # Digits before conversion

    print(f'{r:2} | {x:{n}d}') # Dictionary?....
    while x > 0:
        print(' +' + (n + 2) * '-') # (to make the number of --- according to the number of digits when expressing the expression look neat)
        if x // r:
            print(f'{r:2} | {x // r:{n}d} … {x % r}')
        else:
            print(f'     {x // r:{n}d} … {x % r}')
        d+=dchar[x %r] #Take out the corresponding character and combine it
        x //= r

    returned[::-1] #Return in reverse order