docs: public final QueryParser.nil_return nil() throws RecognitionException {
          QueryParser.nil_return retval = new QueryParser.nil_return();
          retval.start = input.LT(1);
  
          CommonTree root_0 = null;
  
          Token set86=null;
  
          CommonTree set86_tree=null;
  
          try {
              // src/riemann/Query.g:73:5: ( 'null' | 'nil' )
              // src/riemann/Query.g:
              {
              root_0 = (CommonTree)adaptor.nil();
  
              set86=(Token)input.LT(1);
              if ( (input.LA(1)>=29 && input.LA(1)<=30) ) {
                  input.consume();
                  adaptor.addChild(root_0, (CommonTree)adaptor.create(set86));
                  state.errorRecovery=false;
              }
              else {
                  MismatchedSetException mse = new MismatchedSetException(null,input);
                  throw mse;
              }
  
  
              }
  
              retval.stop = input.LT(-1);
  
              retval.tree = (CommonTree)adaptor.rulePostProcessing(root_0);
              adaptor.setTokenBoundaries(retval.tree, retval.start, retval.stop);
  
          }
          catch (RecognitionException re) {
              reportError(re);
              recover(input,re);
      	retval.tree = (CommonTree)adaptor.errorNode(input, retval.start, input.LT(-1), re);
  
          }
          finally {
          }
          return retval;
      }