In the documentation of the functions exported by
irregex), the following conventions for argument names are used:
A string representing a regular expression in POSIX syntax, with PCRE extensions.
A symbolic expression (a list) representing an SRE regular expression in SCSH syntax.
A regular expression in one of the following forms: string in POSIX/PCRE syntax; symbolic expression in SRE syntax; a precompiled regular expression value.
Non–negative, exact integers representing indexes usually into a string. start is the index of the first code point in a selected substring; past is the index of the code point past the last code point included in the selected substring.
Can be any value.