message: K-FAC: clean up error message.
diff: @@ -177,7 +177,7 @@ class FisherEstimator(object):
  elif (not math.isinf(reg_uses)) and reg_uses != total_uses:
  error_messages.append(
  "Variable {} registered with wrong number of uses ({} "
  - "vs {} actual).".format(var, reg_uses, total_uses))
  + "registrations vs {} uses).".format(var, reg_uses, total_uses))
  num_get_vars = len(reg_use_map)
  