Prepare the system for using ``ansible-galaxy`` and returns None.

        :return: None

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)