def new_subcommand(self,
                       name,
                       about='',
                       version='',
                       main=_null_func):
        subcmd = SubCommand(name, version=version, about=about, main=main)
        self.add_subcommand(subcmd)
Ensures instance is not None for ``__get__`` and ``__set__`` methods.
dataset/ETHPy150Open kbknapp/Clapp-py/clapp/clapp.py/App.new_subcommand--crossover with--dataset/ETHPy150Open ulule/django-linguist/linguist/fields.py/instance_only