Convert any-bit number to decimal number and vise versa

Convert any-bit number to decimal number and vise versa.
–bit n to set bit to n
–exp xxx to set expression to xxx
–r to run reversely (from decimal number to any-bit number)
Example:
AB122(16bit) to decimal: python 2deci.py –bit 16 –exp AB122
700706 to 16-bit number: python 2deci.py –bit 16 –exp 700706 –r
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