param obj hidden export function isSet ( obj ) { return Object . prototype . toString . call ( obj ) === '[object Set]' ; } param obj hidden export function isMap ( obj ) { return Object . prototype . toString . call ( obj ) === '[object Map]' ; } param obj hidden export function isIterable ( obj ) { if ( obj == null ) { return false ; } return obj [ Symbol . iterator ] !== undefined ; } param obj hidden export function isIterableConstructor ( obj ) { if ( obj == null || obj . prototype == null ) { return false ; } return obj . prototype [ Symbol . iterator ] !== undefined ; }