Wait for a function to end before continue

[Klingo]

Hi

I have a function that is triggered by an event and within this function there are several sub-functions that are called.
The first sub-functions makes use of some "zo_callLater" and the end of this sub-function is reached earlier than all the "zo_callLater" are ended (they might take 2-3 seconds). So the second sub-function is already called although not all "zo_callLater" from the first sub-function have ended, which causes some problems in the addon.

Currently I deal with this situation in the following way:
The first sub-function returns "true" as soon as all "zo_callLater" calls are completed. I then check this value in a loop if it is "true" and only in that case allow the main function to call the second sub-function.

local mainFunction()
    -- call the first sub-function that contains some 'zo_callLater'
    local isCompleted = callFirstSubFunction()
 
    while (isCompleted == nil) do
        -- do nothing; wait
    end
 
    -- call the second sub-function
    callAnotherSubFunction()
end

It basically works, but I am not sure how bad (performance-wise) this solution is.
I don't see any game-freezing effects like a regular endless-loop would cause, but I thought there might be a better solution for this?

Klingo