code: def reduce_sum(tensors):
      """Returns a tensor with the reduce sum across `tensors`.
  
      The computation is done with a reduce operation, so only one tensor is
      returned.
  
      Args:
        tensors: The input tensors across which to sum; must be assigned
          to GPU devices.
  
      Returns:
        A tensor containing the sum of the input tensors.
  
      Raises:
        LookupError: If context is not currently using a GPU device.
      """
      return _apply_reduce("sum", tensors)
  
file_path: tensorflow/tensorflow/python/ops/nccl_ops.py
imports: import threading
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import device
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import gen_nccl_ops
label_desc: Use image node_id 6 for calling a global function with example usage: reduce_sum(tensors) and returns: _apply_reduce