def to_args(self):
        # type: () -> List[str]
        """
        Return the VCS-specific command arguments.
        """
        args = []  # type: List[str]
        rev = self.arg_rev
        if rev is not None:
            args += self.vcs.get_base_rev_args(rev)
        args += self.extra_args

        return args

        Return the VCS-specific command arguments.
        
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_internal/vcs/__init__.py