class_docstr: Basic test case for `OperatorPool`.
class_docstr_tok: ["Basic","test","case","for","`","OperatorPool","`","."]
code: def setUp(self):
      self._op_pool = OperatorPool()
      self._key = "test"
  
file_path: towhee/tests/unittests/runtime/test_operator_pool.py
imports: import unittest
  from towhee.operator import Operator
  from towhee.runtime.operator_manager import OperatorPool
label_desc: Use image node_id 1 for calling the TestOperatorPool obj's underlying member method code with example usage: obj.setUp() without return types