class_docstr: The registry that provides name -> object mapping, to support third-party users' custom modules.
  To create a registry (inside segmentron):
  .. code-block:: python
      BACKBONE_REGISTRY = Registry('BACKBONE')
  To register an object:
  .. code-block:: python
      @BACKBONE_REGISTRY.register()
      class MyBackbone():
          ...
  Or:
  .. code-block:: python
      BACKBONE_REGISTRY.register(MyBackbone)
code: def get(self, name):
      ret = self._obj_map.get(name)
      if ret is None:
          raise KeyError(
              "No object named '{}' found in '{}' registry!".format(
                  name, self._name
              )
          )
  
      return ret
  
imports: import functools
  import paddle
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 4 for calling the Registry obj's underlying member method code with example usage: obj.get(name) and returns: ret