docs: function(index) {
          var total = index,
              tt;
          if (index > 0) {
              //TODO: Store 5 somewhere
              if (index > 5) {
                  throw new Error("Too much lookahead.");
              }
  
              //get all those tokens
              while (total) {
                  tt = this.get();
                  total--;
              }
  
              //unget all those tokens
              while (total < index) {
                  this.unget();
                  total++;
              }
          } else if (index < 0) {
  
              if (this._lt[this._ltIndex+index]) {
                  tt = this._lt[this._ltIndex+index].type;
              } else {
                  throw new Error("Too much lookbehind.");
              }
  
          } else {
              tt = this._token.type;
          }
  
          return tt;
  
      }