protected function registerMutator(string $operator, $callable, bool $stack = false, string $property = null): self
    {
        $this->mutators[$operator] = [
            'callable' => $callable,
            'stack'    => $stack,
            'property' => $property ?? $this->name,
        ];

        return $this;
    }
protected function registerMutator(string $operator, $callable, bool $stack = false, string $property = null): self
    {
        $this->mutators[$operator] = [
            'callable' => $callable,
            'stack'    => $stack,
            'property' => $property ?? $this->name,
        ];

        return $this;
    }
protected function registerMutator ( string $ operator , $ callable , bool $ stack = false , string $ property = null ) : self { $ this -> mutators [ $ operator ] = [ 'callable' => $ callable , 'stack' => $ stack , 'property' => $ property ?? $ this -> name , ] ; return $ this ; }
Register mutator.

@param string          $operator
@param callable|string $callable
@param bool            $stack
@param string|null     $property

@return MutationHandler
Register mutator .