>>> from functools import partial
>>> def print_full(gauge, power, use, version, subversion=None):
...     print "{}{}{}-{}{}".format(
...         gauge,
...         power,
...         use,
...         version,
...         subversion.lower() if subversion else ''
...     )
...
>>> print_diesel_BG = partial(print_full, gauge='W', power='D')
>>> print_diesel_BG(use='P', version='4')
WDP-4
>>> print_diesel_BG(use='G', version='3', subversion='A')
WDG-3a