code: def __call__(self, x):
      return self.factor + x
  
imports: import unittest
  from towhee.operator.nop import NOPNodeOperator
  from towhee.operator import PyOperator
  from towhee.runtime.pipeline import Pipeline
  from towhee.runtime.data_queue import Empty
  from towhee.runtime import ops, register
  from towhee.runtime.runtime_pipeline import RuntimePipeline
label_desc: Use image node_id 2 for calling the AddOperator obj's underlying member method code with example usage: obj.__call__(x) and returns: unknown