assert_all_are_empty_character
                        Does the input contain empty or missing
                        strings?
assert_all_are_matching_fixed
                        Does the string match a pattern?
assert_all_are_numeric_strings
                        Does the string contain a number/logical value?
assert_all_are_single_characters
                        Is the input a single character?
character_to_list_of_integer_vectors
                        Convert a character vector to a list of integer
                        vectors
create_regex            Create a regex from components.
d                       Create regex for repeated digits
matches_regex           Does the input match the regular expression?
recycle                 Recycle arguments
strip_invalid_chars     Removes invalid characters from a string.
