Integer between 0-6 representing the day of the week (0 = Sunday, 6 = Saturday)
The locale to use for formatting (default: 'en-US')
The format type, either 'long' (e.g., 'Sunday') or 'short' (e.g., 'Sun') (default: 'long')
The localized day name as a string
Converts a day number to a day name in the specified locale and format. Uses 0-based indexing for days (0 = Sunday, 6 = Saturday).