Function isSubset

src/CollectionImpl.js:388–391

(iter)

  hasIn: hasIn,

  isSubset(iter) {
    iter = typeof iter.includes === 'function' ? iter : Collection(iter);
    return this.every((value) => iter.includes(value));
  },

  isSuperset(iter) {
    iter = typeof iter.isSubset === 'function' ? iter : Collection(iter);