function assign(obj, props) {
	for (let i in props) obj[i] = props[i];
	return /** @type {O & P} */ (obj);
}
Assign properties from `props` to `obj`
@template O, P The obj and props types
@param {O} obj The object to copy properties to
@param {P} props The object to copy properties from
@returns {O & P}