anchor.diff:  %%====================================================================
   %% Private Parts
   %%====================================================================
  +
  +validate_histogram_labels(Labels) ->
  +  [raise_error_if_le_label_found(Label) || Label <- Labels].
  +
  +raise_error_if_le_label_found("le") ->
  +  erlang:error({invalid_metric_label_name, "le", "histogram cannot have a label named \"le\""});
  +raise_error_if_le_label_found(Label) ->
  +  Label.
  +
   validate_histogram_bounds([]) ->
     erlang:error({histogram_no_bounds, []});
   validate_histogram_bounds(undefined) ->
  
positive.code: validate_histogram_bound(Bound) ->
    erlang:error({histogram_invalid_bound, Bound}).
  
  
  dobserve_impl(Registry, Name, LabelValues, Value) ->
    case ets:lookup(?TABLE, {Registry, Name, LabelValues}) of
      [Metric]->
  
negative.code:   register(Registry),
    prometheus_metric:insert_mf(?TABLE, Registry, Name, Labels, Help, Bounds).
  
  observe(Name, Value) ->
    observe(default, Name, [], Value).
  
  