I forgot how to use append. Can someone please show me?
Array.append(something)
You can also change the language to java-script and see and use ( I think all ) the js array functions you find in book V ( including push). Then if you want you can find an equivalence in python.
Edit: if I’m not clear -> you can use js functions in python CoCo levels 
Thank you for replying @xython and @Chaboi_3000
I’m good now.