persianDayDay method
English weekday names → Persian. "Monday" → "دو شنبه"
Implementation
String persianDayDay() => replaceAll("Sunday", "یک شنبه")
.replaceAll("Monday", "دو شنبه")
.replaceAll("Tuesday", "سه شنبه")
.replaceAll("Wednesday", "چهار شنبه")
.replaceAll("Thursday", "پنج شنبه")
.replaceAll("Friday", "جمعه")
.replaceAll("Saturday", "شنبه");