def load_installed_version(self):
        installed_packages = get_installed_pypackages()
        if self.package in installed_packages:
            self.version = "=={}".format(
                installed_packages[self.package].version)
def switch(self, dest, url, rev_options):
        # type: (str, HiddenText, RevOptions) -> None
        self.run_command(
            make_command('config', 'remote.origin.url', url),
            cwd=dest,
        )
        cmd_args = make_command('checkout', '-q', rev_options.to_args())
        self.run_command(cmd_args, cwd=dest)

        self.update_submodules(dest)