You can use the commonly appearing cradle to transition into an assassin to finish.
You can see the transition (but not the finish) from Niel Melanson here, which is basically a leg weave/smash pass movement -
(5:40)
- and you can see the start and finish (but not the transition) from this video here -
- and you can also set it up if you get into the smash pass/leg weave itself first too;
This is typical of most material on youtube; it's basically up to you to be able to use your own good sense to tell what details are more gooder, what good details are or are not rivalrous or exclusive with other details, and what good details might work together for a greater cohesive whole.
The cradle is something that shows up in a lot of situations; essentially, any situation where someone is bringing their leg up, putting their knee closer too their head. Particular concern for the submission grappler would be the butterfly guard and knee shield half guard situations, which, it ought be noted are fairly common tactics. It so happens that going directly to head and arm chokes happens to be a common and effective method of attacking these guards, and whether you go to one or the other more or less basically depends on if their reaction to you headhunting is to throw their legs up and/or invert to block you. Which, it ought be noted is also a fairly common tactic amongst those experienced with such positions.