This is a consequence of python not having explicit variable definition. Here it'll decide to define a new x instead of seeing the old one. And that's also usu

This is a consequence of python not having explicit variable definition. Here it'll decide to define a new x instead of seeing the old one. And that's also usually what you want because otherwise a function would start altering variables in the enclosing scope if they happen to exist! E.g. foo = 42 def myfunc(bar): foo = bar + 1 print(foo) myfunc(6) print(foo) # would print "7" if the "foo =" above took the nonlocal foo automatically! So the trade-off is to require "nonlocal" if you ever need a variable from the enclosing scope.