code: private Comparison buildComparison(GDLParser.ComparisonExpressionContext ctx) {
      ComparableExpression lhs = extractComparableExpression(ctx.comparisonElement(0));
      ComparableExpression rhs = extractComparableExpression(ctx.comparisonElement(1));
      Comparator comp = Comparator.fromString(ctx .ComparisonOP().getText());
  
      return new Comparison(lhs, comp, rhs);
    }
docs: Builds a Comparison filter operator from comparison context
  
  @param ctx the comparison context that will be parsed
  @return parsed operator