public override ConsoleString Visit(FormatFunctionElement format, T item)
 {
     if (_functions.TryGetValue(format.Name, out var function))
     {
         return(function.Evaluator(item, format.Arguments.ToImmutableList()));
     }
     else
     {
         return(GetErrorString("UNKNOWN FUNCTION", format.Name));
     }
 }
 public override IEnumerable <FormatVariableElement> Visit(FormatFunctionElement format) => new FormatVariableElement[0];