center function
Center text within width using char for padding.
Implementation
String center(String text, int width, {String char = ' '}) {
if (text.length >= width) return text;
final totalPad = width - text.length;
final leftPad = totalPad ~/ 2;
final rightPad = totalPad - leftPad;
return '${char * leftPad}$text${char * rightPad}';
}