public DateTimeFormatterBuilder Append(DateTimeFormatToken token)
 {
     Checks.NotNull(token);
     _tokens.Enqueue(token);
     return(this);
 }
 public DateTimeFormatterBuilder Append(char literal)
 {
     Checks.NotNull(literal);
     _tokens.Enqueue(DateTimeFormatToken.Of(literal));
     return(this);
 }