`$group` could possibly contain unsafe characters, now that every string input is allowed, so it should be escaped. Also, we have to make sure to not cause any clashes when renaming "a:1" to "a_1" because "a_1" could already exist.

IMO however, it can be removed completely. The old way was to use just incrementing numbers in order to avoid clashes. The actual group name is added as a subgraph label anyway, so I don't think the *real* subgraph name is even needed?

Any thoughts?