I want to allow user to create script within the game, and avoiding it to modify the game's node : https://en.wikipedia.org/wiki/Sandbox_(software_development) :
"A sandbox is a testing environment that isolates untested code changes and outright experimentation from the production environment or repository"
"By further analogy, the term "sandbox" can also be applied in computing and networking to other temporary or indefinite isolation areas, such as security sandboxes [...] that prevent incoming data from affecting a "live" system"
What I want is to isolate a script, created by the user, and giving in only what I want. So, removing the
get_tree() and other functions like this.