docs: def check_version(mod, required):
      """Require minimum version of module using ``__version__`` member."""
      vers = tuple(int(v) for v in mod.__version__.split('.')[:3])
      if vers < required:
          req = '.'.join(str(v) for v in required)
          raise ImproperlyConfigured(
              "Module \"%s\" version (%s) must be >= %s." %
              (mod.__name__, mod.__version__, req))