code: public final BELScriptWalker.unset_statement_group_return unset_statement_group() throws RecognitionException {
          BELScriptWalker.unset_statement_group_return retval = new BELScriptWalker.unset_statement_group_return();
          retval.start = input.LT(1);
  
          CommonTree root_0 = null;
  
          CommonTree _first_0 = null;
          CommonTree _last = null;
  
          CommonTree string_literal20=null;
          CommonTree STATEMENT_GROUP_KEYWORD21=null;
  
          CommonTree string_literal20_tree=null;
          CommonTree STATEMENT_GROUP_KEYWORD21_tree=null;
  
          try {
              // BELScriptWalker.g:278:22: ( 'UNSET' STATEMENT_GROUP_KEYWORD )
              // BELScriptWalker.g:279:5: 'UNSET' STATEMENT_GROUP_KEYWORD
              {
              root_0 = (CommonTree)adaptor.nil();
  
              _last = (CommonTree)input.LT(1);
              string_literal20=(CommonTree)match(input,26,FOLLOW_26_in_unset_statement_group261); 
              string_literal20_tree = (CommonTree)adaptor.dupNode(string_literal20);
  
              adaptor.addChild(root_0, string_literal20_tree);
  
              _last = (CommonTree)input.LT(1);
              STATEMENT_GROUP_KEYWORD21=(CommonTree)match(input,STATEMENT_GROUP_KEYWORD,FOLLOW_STATEMENT_GROUP_KEYWORD_in_unset_statement_group263); 
              STATEMENT_GROUP_KEYWORD21_tree = (CommonTree)adaptor.dupNode(STATEMENT_GROUP_KEYWORD21);
  
              adaptor.addChild(root_0, STATEMENT_GROUP_KEYWORD21_tree);
  
  
                      activeStatementGroup = null;
                      sgAnnotationContext.clear();
                  
  
              }
  
              retval.tree = (CommonTree)adaptor.rulePostProcessing(root_0);
  
          }
          catch (RecognitionException re) {
              reportError(re);
              recover(input,re);
          }
          finally {
          }
          return retval;
      }
docs: BELScriptWalker.g:278:1: unset_statement_group : 'UNSET' STATEMENT_GROUP_KEYWORD ;