---ENVIRONMENT ONE---
x = print --save
print = function() end
print("A") --doesn't print anything: print has been set to an empty function
local environment = getfenv() --save the current environment: a table containing x and print


--ENVIRONMENT TWO---
setfenv(1, {print = x, setfenv = setfenv}) --set the new environment, setting print to the saved print
print("hi") --prints 'hi', print's environment has been changed


--ENVIRONMENT ONE---
setfenv(1, environment)
print("A") --doesn't print anything: revereted back to the original environment