Build, test, and debug regular expressions
Matches commas that separate sets or members while excluding commas nested inside square-bracket or curly-brace delimited groups, using negative lookaheads to detect upcoming closing brackets. It also matches all curly braces `{` and `}` themselves. Useful for splitting nested structured data (e.g., lists of sets) on top-level delimiters while preserving commas within bracketed members.