class_docstr: Test Pipeline
class_docstr_tok: ["Test","Pipeline"]
code: def test_flat_map(self):
      pipe = (
          Pipeline.input("a")
          .flat_map("a", "b", ops.local.flat_operator())
          .output("b")
      )
      res = pipe([1, 2])
      self.assertEqual(res.get()[0].num, 1)
      self.assertEqual(res.get()[0].num, 2)
  
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 14 for calling the TestPipeline obj's underlying member method code with example usage: obj.test_flat_map() without return types