class_docstr: Coverage
class_docstr_tok: ["Coverage"]
code: def test_reduce_coverage(self):
      p = (
          Pipeline.input("a")
          .flat_map("a", "a", lambda x: list(range(1, x + 1)))
          .filter("a", "b", "a", lambda x: x > 100)
          .reduce("b", "a", sum)
          .output("a")
      )
      res = p(4).to_list()
      self.assertEqual(res, [[0]])
  
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 4 for calling the TestPipelineColCoverage obj's underlying member method code with example usage: obj.test_reduce_coverage() without return types