Add a lock block

Yea, the title is kinda cryptic, but I want is a block that would act as a throttle but the delay would be infinite until the code inside it ends. So the code inside it won't run at the same time:

So like this:

on a button press:
    lock while running:
         summon enemy
         pause 1 sec

If I press A 2 times with a delay of 250 ms in a second, then it would only summon 1 enemy. But if I press it 4 times with a delay of 500 ms over 2 seconds, then it would summon 2 enemies.

The issue does not name files or tests. Start by locating the existing throttle implementation and the code that handles timer-related blocks, then compare their behavior with the proposed lock examples. Done means repeated button presses are serialized so a new invocation starts only after the prior block finishes.