It happens regularly that the python code i am writing simply doesn't run. I try to stop and nothing happens. I refresh the page i get the same problem. Few hours later i try and everything runs smoothly.
I really would like to use Repl but i am having so many headheache that i am tempted to find another solution :(
I found this to happen sometimes too. An easy fix is to just close your browser and reopen it, and use CTRL+SHIFT+T to open your old pages again - seems to work. Hope this helped.