code: function last(newitem) {
      if (newitem) {
        this.mappings.push({});
      }
  
      var m = this.mappings[this.mappings.length - 1];
  
      if (m && m.attribute && m.value && m.dataKey && m.replace) {
        m.re = new RegExp(m.attribute + '=([\'"]?)' + m.value + '\\1');
      } else if (m) {
        delete m.re;
      }
  
      return m;
    }
docs: ### function last(newitem) #### @newitem {Boolean} do we need to add a new item to the mapping Helper function for adding new attribute maps to a Mapper instance