typical kata solution in python, nice one

Nice kata, pretty simple and pretty hard.
But 'input' is reserved word in Python, it'd be nice to change it.

Yep, this problem is still here. First two lines of tests should be replaced to:
bin = Alphabet['BINARY']; oct = Alphabet['OCTAL']; dec = Alphabet['DECIMAL']; hex = Alphabet['HEXA_DECIMAL'];
allow = Alphabet['ALPHA_LOWER']; alup = Alphabet['ALPHA_UPPER']; alpha = Alphabet['ALPHA']; alnum = Alphabet['ALPHA_NUMERIC'];