code: function storageFor(key, modelName, options = {}) {
    if (arguments.length === 2 && typeof modelName === 'object') {
      options = modelName;
      modelName = null;
    }
  
    assert('The options argument must be an object', typeof options === 'object');
  
    // normalize key
    key = dasherize(key);
  
    if (!modelName) {
      return computed(function() {
        if (!storages[key]) {
          storages[key] = createStorage(this, key, null, options);
        }
  
        return storages[key];
      });
    }
  
    assert('The second argument must be a string', typeof modelName === 'string');
  
    return computed(modelName, function() {
      const model = this.get(modelName);
  
      // if the propertyValue is null/undefined we simply return null/undefined
      if (!model || typeof model === 'undefined') {
        return model;
      }
  
      const modelKey = _modelKey(model);
      const storageKey = `${key}:${modelKey}`;
      // TODO allow callbacks to delete the storage if model gets deleted
  
      if (!storages[storageKey]) {
        storages[storageKey] = createStorage(this, key, modelKey, options);
      }
  
      return storages[storageKey];
    });
  }
docs: TODO: v2.0 - Remove options