Here’s a very easily developed password generator for Python.

>>> import string, random
>>> def passgen(length) :
... keys = list(string.ascii_letters + string.digits + ".,;:-_()@"\[]?!'^+*$%&/=~`<>|")
... return "".join(random.choice(keys) for i in range(length))
>>> passgen(15)
'ziB@I~/hh[Ij]n%'
>>> passgen(6)
'yNe(~r'
>>> passgen(16)
'pP!3p"(-uxdIqpAK'
>>> passgen(25)
'x5t>m/kx%`^_s7jVx?)RmsG5|'

If you only want ascii and digits then it’s obvious what to do I guess?