regexp-opt-group
regexp-opt-group is a compiled Lisp function in `regexp-opt.el
'.
(regexp-opt-group STRINGS &optional PAREN LAX)
Return a regexp to match a string in the sorted list STRINGS.
If PAREN non-nil, output regexp parentheses around returned regexp.
If LAX non-nil, don't output parentheses if it doesn't require them.
Merges keywords to avoid backtracking in Emacs's regexp matcher.