How can PHP developers ensure that their code accurately reflects the desired start of the calendar week, such as on a Saturday?

When working with calendars in PHP, developers can ensure that their code accurately reflects the desired start of the calendar week by setting the first day of the week using the `date()` function with the `'w'` format specifier. By setting the first day of the week to Saturday (which is represented by the value 6 in PHP), developers can ensure that their calendar calculations align with their desired start of the week.

// Set the first day of the week to Saturday (6)
// This will make Saturday the first day of the week in calendar calculations
date_default_timezone_set('UTC');
$firstDayOfWeek = 6;
echo date('Y-m-d', strtotime('last saturday'));