if (!expr.isEqualityComparison(String.class, GString.class)) return null;
// values can't be null here
String str1 = expr.getChildren().get(0).getValue().toString();
String str2 = expr.getChildren().get(1).getValue().toString();
EditDistance dist = new EditDistance(str1, str2);
return String.format("false\n%d difference%s (%d%% similarity)\n%s",
dist.getDistance(), dist.getDistance() == 1 ? "" : "s", dist.getSimilarityInPercent(),
new EditPathRenderer().render(str1, str2, dist.calculatePath()));
}