toInteger return type string

[root-aza]

Hi! I would like to discuss this interface: https://github.com/php-identifier/identifier/blob/main/src/IntegerIdentifier.php#L20C21-L20C30

In my opinion, the toInteger method should always return a string.

The main problems with the union type are:

• need for additional type checking
• complicating static analysis
• side effects when used