code: def register_proxy_type(cls, real_type, proxy_type):
          
          if distob.engine is None:
              cls._initial_proxy_types[real_type] = proxy_type
          elif isinstance(distob.engine, ObjectHub):
              distob.engine._runtime_reg_proxy_type(real_type, proxy_type)
          else:
              # TODO: remove next line after issue #58 in dill is fixed.
              distob.engine._singleeng_reg_proxy_type(real_type, proxy_type)
              pass
docs: Configure engines so that remote methods returning values of type
          `real_type` will instead return by proxy, as type `proxy_type`