Calendar_style TextFormatter dayTextFormatter more details

[Quardah]

In the code for calendar_style.dart we see the following statement to try setting up dayTextFormatter:

/// Use to customize the text within each day cell.
/// Defaults to '${date.day}', to show just the day number.
///
/// Example usage:
/// dart /// dayTextFormatter: (date, locale) => DateFormat.d(locale).format(date), ///
final TextFormatter? dayTextFormatter;

I am unable to get it to work, i would like to ask for more details. I am new to this.

What i am trying to do is have the date displayed on the top left corner of the cell and have the center of the cell displaying a letter chosen by the user. I do have the intl package imported

import 'package:intl/intl.dart';

Thank you.