function hashSet(key, value) {
  var data = this.__data__;
  this.size += this.has(key) ? 0 : 1;
  data[key] = (nativeCreate && value === undefined) ? HASH_UNDEFINED : value;
  return this;
}
Sets the hash `key` to `value`.

@private
@name set
@memberOf Hash
@param {string} key The key of the value to set.
@param {*} value The value to set.
@returns {Object} Returns the hash instance.