code: def cross_replica_sum(x, group_assignment=None, name=None):
      """Sum the input tensor across replicas according to group_assignment.
  
      Args:
        x: The local tensor to the sum.
        group_assignment: Optional 2d int32 lists with shape [num_groups,
          num_replicas_per_group]. `group_assignment[i]` represents the replica ids
          in the ith subgroup.
        name: Optional op name.
  
      Returns:
        A `Tensor` which is summed across replicas.
      """
      if group_assignment is None:
          group_assignment = _create_default_group_assignment()
  
      return gen_tpu_ops.cross_replica_sum(
          x, group_assignment, name=name
      )
  
imports: from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gen_tpu_ops
  from tensorflow.python.ops.gen_tpu_ops import *
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.tpu import tpu_function
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 4 for calling a global function with example usage: cross_replica_sum(x, group_assignment, name) and returns: gen_tpu_ops