redirect_aliases = chain(* map(lambda obj: obj.get("aliases"), redirect_config))
                 redirect_aliases = list(map(lambda s: s.lstrip('#'), redirect_aliases))
                 redirect_aliases.append('REDIRECT') # just in case
+
+                # this regular expression is copied from pywikibot
                 pattern = '(?:' + '|'.join(redirect_aliases) + ')'
                 redirect_regex =  re.compile(r'\s*#{pattern}\s*:?\s*\[\[(.+?)(?:\|.*?)?\]\]'
                                              .format(pattern=pattern), re.IGNORECASE | re.DOTALL)