When the first edition was written, there was no built in Gremlin support for regular expressions. Starting with the TinkerPop 3.6.0 release, a new text predicate regex was added. An inverse step, notRegex, was also added. There are several places in the book where the lack of built in regular expressions is discussed. A way to build a custom predicate is also discussed. The manuscript should now be updated to reflect the new Gremlin steps.