code: def _setup_fd(fd):
      
  
      # Make the file nonblocking (but don't lose its previous flags)
      flags = fcntl.fcntl(fd, fcntl.F_GETFL)
      fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK)
      set_buf_size(fd)
docs: Common set-up code for initializing a (pipe) file descriptor