class_docstr: Test Pipeline
class_docstr_tok: ["Test","Pipeline"]
code: def test_batch_single_input(self):
      pipe = (
          Pipeline.input("a").map("a", "c", lambda x: x + 2).output("c")
      )
      batch_inputs = [1, 2, 3, 4]
      res = pipe.batch(batch_inputs)
      for idx, item in enumerate(res):
          self.assertEqual(item.get()[0], batch_inputs[idx] + 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 22 for calling the TestPipeline obj's underlying member method code with example usage: obj.test_batch_single_input() without return types