code: def inject_function(target_cls, *injected_cls):
      """
      Inject function to base directly.
  
      :param target_cls:      nano extended class, e.g. nano.tf.keras.Model
      :param injected_cls:    class with extended method for tf base
      """
      for cls in injected_cls:
          for name in dir(cls):
              if not name.startswith("_"):
                  if name in dir(target_cls):
                      old_f = getattr(target_cls, name)
                      setattr(target_cls, name + "_old", old_f)
                      setattr(target_cls, name, getattr(cls, name))
                  else:
                      setattr(target_cls, name, getattr(cls, name))
  
label_desc: Use image node_id 1 for calling a global function with example usage: inject_function(target_cls) without return types