x = 100 def outer(): global x x = 'hello' def inner1(): #nonlocal x; with this line, error arises. Cause it conflicts with global in the top layer of function x = 'python' def inner2(): nonlocal x x = 'monty' print('inner1 (before):', x) inner2() print('inner1 (after):', x) inner1() print('outer:', x) outer() # line sequence: 16, 2, 3, 4 14, 5, 7, 11, 12, 8, 9, 10, 13, 15 #inside inner2, x change from python to monty, #insdie inner1, x is python. #insdie outer, x is hello as global declared