src/Mapper.php
private function add(
        string $property,
        ?InstructsHowToMap $instruction
    ): array {
        return $this->properties + [$property => $instruction ?: Is::string()];
    }
private function add(
        string $property,
        ?InstructsHowToMap $instruction
    ): array {
        return $this->properties + [$property => $instruction ?: Is::string()];
    }
private function add ( string $ property , ? InstructsHowToMap $ instruction ) : array { return $ this -> properties + [ $ property => $ instruction ? : Is :: string ( ) ] ; }
Adds a property to the mapper.

@param string                 $property    The name of the property.
@param InstructsHowToMap|null $instruction The instruction to follow.
@return InstructsHowToMap[]                The map of properties to
mapping instructions.
Adds a property to the mapper .