from tensorflow.python.framework import constant_op

from tensorflow.python.ops import math_ops
from tensorflow.python.ops import state_ops
from tensorflow.python.ops.control_flow_ops import with_dependencies
from tensorflow.python.training import session_run_hook


def _streaming_sum(scalar_tensor):
  """Create a sum metric and update op."""
  sum_metric = framework.local_variable(constant_op.constant(0.0))
  sum_update = sum_metric.assign_add(scalar_tensor)
  return sum_metric, sum_update


class _InitializeClustersHook(session_run_hook.SessionRunHook):
  """Initializes clusters or waits for cluster initialization."""

