src/lib/methods/set.js
function set(store, key, value, options) {
  return doSet(store, key, value, Object.assign({}, DEFAULT_OPTIONS, options));
}
function set(store, key, value, options) {
  return doSet(store, key, value, Object.assign({}, DEFAULT_OPTIONS, options));
}
Store 'value' at 'key'
@param {DataStore} store
@param {String} key
@param {*} value
@param {Object} [options]
- {Boolean} immutable
- {Boolean} merge
@returns {Boolean}