code: def reduce_connection(conn):
      df = DupFd(conn.fileno())
      return rebuild_connection, (df, conn.readable, conn.writable)
  
file_path: catboost/contrib/python/joblib/joblib/externals/loky/backend/_posix_reduction.py
imports: import os
  import socket
  import _socket
  from multiprocessing.connection import Connection
  from multiprocessing.context import get_spawning_popen
  from .reduction import register
label_desc: Use image node_id 6 for calling a global function with example usage: reduce_connection(conn) and returns: rebuild_connection,  df,  conn,  conn