code: function clone() {
      var cloned = new this.constructor(this.client);
      cloned._method = this._method;
      cloned._single = assign({}, this._single);
      cloned._options = assign({}, this._options);
      cloned._statements = this._statements.slice();
      return cloned;
    }
docs: Create a shallow clone of the current query builder. TODO: Test this!!