class_docstr: Reduce node.
  
  Reduce the sequence to a single value
class_docstr_tok: ["Reduce","node",".","Reduce","the","sequence","to","a","single","value"]
code: def get_col(self, key: str):
      while True:
          if len(self._col_cache[key]) != 0:
              yield self._col_cache[key].popleft()
              continue
  
          with self._lock:
              if len(self._col_cache[key]) != 0:
                  yield self._col_cache[key].popleft()
                  continue
  
              if (
                  self._read_from_dq()
                  and len(self._col_cache[key]) != 0
              ):
                  yield self._col_cache[key].popleft()
                  continue
          break
  
file_path: towhee/towhee/runtime/nodes/_reduce.py
imports: import threading
  from typing import List
  from collections import deque
  from towhee.runtime.time_profiler import Event
  from towhee.runtime.data_queue import Empty
  from .node import Node
  from ._single_input import SingleInputMixin
label_desc: Use image node_id 3 for calling the Reduce obj's underlying member method code with example usage: obj.get_col(key) without return types