DateTimeImmutable
DateTimeImmutable::__construct
DateTimeImmutable
PHP Manual

# DateTimeImmutable::add

(PHP 5 >= 5.5.0)

DateTimeImmutable::add — Adds an amount of days, months, years, hours, minutes and seconds

### Description

public DateTimeImmutable DateTimeImmutable::add ( DateInterval `$interval` )

Like DateTime::add() but works with DateTimeImmutable.

DateTimeImmutable
DateTimeImmutable::__construct
DateTimeImmutable
PHP Manual