1f.py

def f1():
    a = 0
    a += 1

dis.dis(f1)

1o.dis

  2           0 LOAD_CONST               1 (0)
              3 STORE_FAST               0 (a)

  3           6 LOAD_FAST                0 (a)
              9 LOAD_CONST               1 (1)
             12 INPLACE_ADD         
             13 STORE_FAST               0 (a)
             16 LOAD_CONST               0 (None)
             19 RETURN_VALUE  

2f.py

def f2():
    a = 0
    a = a + 1

2o.dis

  2           0 LOAD_CONST               1 (0)
              3 STORE_FAST               0 (a)

  3           6 LOAD_FAST                0 (a)
              9 LOAD_CONST               1 (1)
             12 BINARY_ADD          
             13 STORE_FAST               0 (a)
             16 LOAD_CONST               0 (None)
             19 RETURN_VALUE   

3f.py

def f3():
    a = []
    a += [1]

3o.dis

  2           0 BUILD_LIST               0
              3 STORE_FAST               0 (a)

  3           6 LOAD_FAST                0 (a)
              9 LOAD_CONST               1 (1)
             12 BUILD_LIST               1
             15 INPLACE_ADD         
             16 STORE_FAST               0 (a)
             19 LOAD_CONST               0 (None)
             22 RETURN_VALUE        

4f.py

def f4():
    a = []
    a.extend([1])

4o.dis

  2           0 BUILD_LIST               0
              3 STORE_FAST               0 (a)

  3           6 LOAD_FAST                0 (a)
              9 LOAD_ATTR                0 (extend)
             12 LOAD_CONST               1 (1)
             15 BUILD_LIST               1
             18 CALL_FUNCTION            1
             21 POP_TOP             
             22 LOAD_CONST               0 (None)
             25 RETURN_VALUE        

5f.py

def f5():
    a = [5]
    a[0] += 1

5o.dis

  2           0 LOAD_CONST               1 (5)
              3 BUILD_LIST               1
              6 STORE_FAST               0 (a)

  3           9 LOAD_FAST                0 (a)
             12 LOAD_CONST               1 (0)
             15 DUP_TOPX                 2
             18 BINARY_SUBSCR       
             19 LOAD_CONST               2 (1)
             22 INPLACE_ADD         
             23 ROT_THREE           
             24 STORE_SUBSCR        
             25 LOAD_CONST               0 (None)
             28 RETURN_VALUE        

6f.py

def f6():
    a = ([],)
    a[0] += [1]

6o.dis

  2           0 BUILD_LIST               0
              3 BUILD_TUPLE              1
              6 STORE_FAST               0 (a)

  3           9 LOAD_FAST                0 (a)
             12 LOAD_CONST               1 (0)
             15 DUP_TOPX                 2
             18 BINARY_SUBSCR       
             19 LOAD_CONST               2 (1)
             22 BUILD_LIST               1
             25 INPLACE_ADD         
             26 ROT_THREE           
             27 STORE_SUBSCR        
             28 LOAD_CONST               0 (None)
             31 RETURN_VALUE