code: def load_subclasses(klass, modules=None):
      
      if modules:
          if isinstance(modules, six.string_types):
              modules = [modules]
          loader = Loader()
          loader.load(*modules)
      return klass.__subclasses__()
docs: Load recursively all all subclasses from a module.
  
      Args:
          klass (str or list of str): Class whose subclasses we want to load.
          modules: List of additional modules or module names that should be
              recursively imported in order to find all the subclasses of the
              desired class. Default: None
  
      FIXME: This function is kept only for backward compatibility reasons, it
          should not be used. Deprecation warning should be raised and it should
          be replaces by the ``Loader`` class.