rx                      Constructs a Verbal Expression
rx_alnum                Match alphanumeric characters.
rx_alpha                Match alphabetic characters.
rx_any_of               Match any of these characters exactly once.
rx_anything             Match any character(s) any (including zero)
                        number of times.
rx_anything_but         Match any character(s) except these any
                        (including zero) number of times.
rx_avoid_prefix         Negative lookaround functions
rx_begin_capture        Begin a capture group.
rx_digit                Match a digit (0–9).
rx_either_of            Alternatively, match either expression.
rx_end_capture          End a capture group.
rx_end_of_line          Match the expression only if it appears till
                        the end of the line.
rx_find                 Match an expression.
rx_line_break           Match a line break.
rx_lowercase            Match lower case letters.
rx_maybe                Optionally match an expression.
rx_multiple             Match the previous group any number of times.
rx_none_or_more         Match the previous stuff zero or many times.
rx_not                  Ensure that the parameter does not follow.
rx_one_or_more          Match the previous stuff one or more times.
rx_punctuation          Match punctuation characters.
rx_range                Match any character within the range defined by
                        the parameters.
rx_seek_prefix          Positive lookaround functions
rx_something            Match any character(s) at least once.
rx_something_but        Match any character(s) except these at least
                        once.
rx_space                Match a space character.
rx_start_of_line        Match the expression only if it appears from
                        beginning of line.
rx_tab                  Match a tab character.
rx_uppercase            Match upper case letters.
rx_whitespace           Match a whitespace character.
rx_with_any_case        Control case-insensitive matching.
rx_word                 Match a word.
rx_word_char            Match a word character.
rx_word_edge            Find beginning or end of a word.
sanitize                Escape characters expected special by regex
                        engines
