docs: function BaseMiddleware (Model, key) {
    // constructor
    var instance = function (req, res, next) {
      return instance.exec()(req, res, next);
    };
    instance.Model = Model;
    instance.methodChain = [];
  
    instance.__proto__ = this.__proto__;
  
    instance.setKey = function (key) {
      key = key || Model.modelName.toLowerCase();
      instance.modelKey = inflect.singularize(key);
      instance.collectionKey = inflect.pluralize(key);
    };
    instance.setKey(key);
    return instance;
  }