If you are working with bitcoin weekly charts, or any other ticker with a low amount of price history this function may help you out. For example you want to apply indicators to some shitcoin that just launched? This can help you.
It can be frustrating to use certain built-ins since they will only give an output once the full lookback length is available. This function allows you to avoid that situation and start plotting things with almost no history whatsoever!
In this example code we do it by utilizing a replacement for the built in pine SMA function. This function allows us to pass a series instead of just a simple int to the length variable of the SMA. This can be achieved with all the pine built ins and I believe @PineCoders has a publication already detailing many of them with full coded examples.
Then we replace the length of the SMA with the custom history function. It checks to see if the current bar index is less than the length of the function. Then if it is, it changes the length to the bar index allowing us to get plots and series earlier than otherwise possible.