my_str_1 = "1: outside of func"
my_str_2 = "2: outside of func"
def func():
    my_str_1 = "1: inside the func"
    my_str_2 = "2: inside the func"
    class C:
        print(my_str_1)
        print(my_str_2)
        my_str_1 = "1: inside the class"
func()
>>> outside of func
>>> inside the func

a = 1
def func1():
    print  a
def func2():
    print  a
    a = 2
func1()
func2()

      4 def func2():
----> 5     print  a
      6     a = 2
      7 
UnboundLocalError: local variable 'a' referenced before assignment

>>> import dis
>>> dis.dis(func2)
  2           0 LOAD_FAST                0 (a)
              3 PRINT_ITEM          
              4 PRINT_NEWLINE       
  3           5 LOAD_CONST               1 (2)
              8 STORE_FAST               0 (a)
             11 LOAD_CONST               0 (None)
             14 RETURN_VALUE