ASCII_ALPHA             Class Constants
Anchors                 The start or end of a string.
Backreferences          Backreferences
ClassGroups             Class Groups
Concatenation           Combine strings together
DateTime                Date-time regexes
SpecialCharacters       Special characters
Unicode                 Unicode groups
WordBoundaries          Word boundaries
as.regex                Convert or test for regex objects
capture                 Capture a token, or not
char_class              A range or char_class of characters.
escape_special          Escape special characters
exactly                 Make a regex exact
format.regex            Print or format regex objects
get_weekdays            Get the days of the week
literal                 Treat part of a regular expression literally.
lookahead               Lookaround
number_range            Generate a regular expression for a number
                        range.
or                      Alternation
recursive               Make the regular expression recursive.
recycle                 Recycle arguments
regex                   Create a regex
repeat_in_class         Engine for grouping and repeating classes
repeated                Repeat values
