https://spannbaueradam.shinyapps.io/r_regex_tester/ http://rextester.com/l/r_online_compiler
ICU's Regular Expression loosely based on JDK 1.4 java.util.regex with some extensions. Used in R's stringi/stringr.
Regular Expressions as used in R
library(stringi) stri_escape_unicode(mylist[[7]][135,2])