src/lib/methods/set.js
function doSet(store, key, value, options) {
  if (!key || typeof key !== 'string') {
    return false;
  }

  // Returns same if no change
  const newData = property.set(store._data, key, value, options);

  if (options.immutable) {
    if (newData !== store._data) {
      store._data = newData;
    } else {
      store.debug('WARNING no change after set "%s', key);
      return false;
    }
  }

  return true;
}
function doSet(store, key, value, options) {
  if (!key || typeof key !== 'string') {
    return false;
  }

  // Returns same if no change
  const newData = property.set(store._data, key, value, options);

  if (options.immutable) {
    if (newData !== store._data) {
      store._data = newData;
    } else {
      store.debug('WARNING no change after set "%s', key);
      return false;
    }
  }

  return true;
}
Store 'value' at 'key'
@param {DataStore} store
@param {String} key
@param {*} value
@param {Object} [options]
- {Boolean} immutable
- {Boolean} merge
@returns {Boolean}