function push_prop(prop, delay = false) {
		const do_push = () => {
			const current = props_and_spreads.at(-1);
			const current_is_props = Array.isArray(current);
			const props = current_is_props ? current : [];
			props.push(prop);
			if (!current_is_props) {
				props_and_spreads.push(props);
			}
		};

		if (delay) {
			delayed_props.push(do_push);
		} else {
			do_push();
		}
	}
@param {Property} prop
@param {boolean} [delay]