Two minutes of google will inform you of places deque is used, that you don’t understand the language and are therefore cursing it due to your lack of knowledge isn’t helping your cause when asking questions. Neither is the fact that your attitude towards others means there will be a tendency towards not wanting to offer assistance.
I literally typed in “blender python deque” to google, it led me here, which gives you a rough indication of how it is used by people who use it discussing it. That you don’t know what a function is, how it is called, what return values are does not make the whole coding language stupid.