code: def build_nccl_then_recursive_hd(input_tensors, red_op, un_op=None):
      """Construct hybrid of NCCL within workers, Recursive-HD across workers."""
      upper_level_f = lambda x: build_recursive_hd_all_reduce(
          x, red_op, un_op
      )
      return _build_nccl_hybrid(input_tensors, red_op, upper_level_f)
  
imports: import collections
  import math
  from tensorflow.python.framework import device
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import nccl_ops
label_desc: Use image node_id 22 for calling a global function with example usage: build_nccl_then_recursive_hd(input_tensors, red_op, un_op) and returns: _build_nccl_hybrid