def a():
	exec("AD = (1,2,3,4,5,6);")
	for i in AD:
		print(i)

a()
--------------
linux-xk05:/home/zenix/Desktop # python3 py.py
Traceback (most recent call last):
  File "py.py", line 6, in <module>
    a()
  File "py.py", line 3, in a
    for i in AD:
NameError: name 'AD' is not defined