src/Instruction/Is.php
private static function type(
        string $className,
        string $constructor = self::SAME_KEY,
        string $key = null
    ): DefinesTheType {
        return new Is($className, $constructor, [], $key);
    }
private static function type(
        string $className,
        string $constructor = self::SAME_KEY,
        string $key = null
    ): DefinesTheType {
        return new Is($className, $constructor, [], $key);
    }
private static function type ( string $ className , string $ constructor = self :: SAME_KEY , string $ key = null ) : DefinesTheType { return new Is ( $ className , $ constructor , [ ] , $ key ) ; }
Declare that the property is of the type.

@param string      $className   Class name of the property mapping.
@param string      $constructor Constructor name to use.
@param string|null $key         Data key to use.
@return DefinesTheType       The mapping instruction.
Declare that the property is of the type .