<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _setup(self):
 """ Prepare the system for using ``ansible-galaxy`` and returns None. :return: None """

        role_directory = os.path.join(self._config.scenario.directory,
                                      self.options['roles-path'])
        if not os.path.isdir(role_directory):
            os.makedirs(role_directory)