function containsValue(obj, val) {
  for (const key in obj) {
    if (obj[key] == val) {
      return true;
    }
  }
  return false;
}
Whether the object/map/hash contains the given value. This is O(n).
@param {?Object<K,V>} obj The object in which to look for val.
@param {V} val The value for which to check.
@return {boolean} true If the map contains the value.
@template K,V