How to save the current goal/subgoal as an assert lemma

Question

During a proof, I come to a situation where the current goal/subgoal turned out to be useful in a later stage of the same theorem.

Is there a tactic to "save" the current goal as a lemma as if the current goal is asserted?

Of course, I can copy&paste to assert the goal explicitly, or write a separate Lemma before the current theorem. But I am just curious if shortcuts exist.

Answer

Leaving this answer for future reference.

I don't know since when it exists, but maybe the abstract tactic could help. It allows you to name a part of the proof and re-use it later, even if you are in a different sub-goal.