def op_list_venvs(self):
        """Prints out and returns a list of known virtual environments.

        :rtype: list
        :return: list of virtual environments
        """
        self.logger.info('Listing known virtual environments ...')
        venvs = self.get_venvs()
        for venv in venvs:
            self.logger.info('Found `%s`' % venv)
        else:
            self.logger.info('No virtual environments found in `%s` directory.' % VENVS_DIRNAME)
        return venvs
Prints out and returns a list of known virtual environments.

        :rtype: list
        :return: list of virtual environments