type = $type; return $this; } public function set_label( string $label ): self { $this->label = $label; return $this; } public function add_variant( Style_Variant $variant ): self { $this->variants[] = $variant->build(); return $this; } public function build( string $id ): array { return [ 'id' => $id, 'type' => $this->type, 'label' => $this->label, 'variants' => $this->variants, ]; } }