anchor.diff:  }
   
   @header {
  -    import static org.apache.groovy.parser.antlr4.SemanticPredicates.*;
       import java.util.Deque;
       import java.util.ArrayDeque;
       import java.util.Map;
  
positive.code:     import java.util.Collections;
      import java.util.Arrays;
      import java.util.stream.IntStream;
  }
  
  @members {
  
negative.code:         }
      }
  
      private static final Map<String, String> PAREN_MAP =
          Maps.of(
              "(", ")",
              "[", "]",
              "{", "}"
          );
  
      protected void enterParenCallback(String text) {}
  
  