class_docstr: Test Pipeline
class_docstr_tok: ["Test","Pipeline"]
code: def test_lambda(self):
      pipe = (
          Pipeline.input("a").map("a", "c", lambda x: x + 2).output("c")
      )
      res = pipe(2).get()
      self.assertEqual(res[0], 4)
  
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 5 for calling the TestPipeline obj's underlying member method code with example usage: obj.test_lambda() without return types