The documentation is ambiguous: >DateTimeImmutable::modify — Alters the timestamp As you have said, it creates a copy, it doesn't alter the object. Compare i

The documentation is ambiguous: >DateTimeImmutable::modify — Alters the timestamp As you have said, it creates a copy, it doesn't alter the object. Compare it to Python documentation, ex. str.capitalize()[1]: >Return a copy of the string with its first character capitalized and the rest lowercased. [1]: https://docs.python.org/3/library/stdtypes.html#str.capitalize https://docs.python.org/3/library/stdtypes.html#str.capitali...