anchor.diff:       ,{6, info, "Informational: informational messages"}
        ,{7, debug, "Debug: debug-level messages"}].
   
  +-spec severity_to_int(severity()) -> 0..7.
   severity_to_int(I) when is_integer(I) ->
       I;
   severity_to_int(A) when is_atom(A) ->
  
positive.code:      Process,
       io_lib:format(Fmt, Args)}.
  
  facilities() ->
      [ { 0, kernel, "kernel messages"}
       ,{ 1, user, "user-level messages"}
  
negative.code:      ,{22, local6, "local use 6  (local6)"}
       ,{23, local7, "local use 7  (local7)"}].
  
  -spec facility_to_int(facility()) -> 0..127.
  facility_to_int(I)
    when is_integer(I), 0 =< I, I =< 127 ->
      I;
  facility_to_int(A) when is_atom(A) ->
      element(1, lists:keyfind(A, 2, facilities())).
  
  -type severity() :: 0..7 |
                      'emergency' |
                      'alert' |
                      'critical' |
                      'error' |
                      'warning' |
                      'notice' |
                      'info' |
                      'debug'.
  severities() ->
      [ {0, emergency, "Emergency: system is unusable"}
       ,{1, alert, "Alert: action must be taken immediately"}
  