global vs nonglobal.py

In [9]: def foo():
   ...:     return x
   ...: def foofoo(x):
   ...:     return x
   ...: def bar():
   ...:     x += 1
   ...: def foobar():
   ...:     global x
   ...:     x += 1
   ...:
   ...:

In [10]: dis.dis(foo)
  2           0 LOAD_GLOBAL              0 (x)
              2 RETURN_VALUE

In [11]: dis.dis(foofoo)
  4           0 LOAD_FAST                0 (x)
              2 RETURN_VALUE

In [12]: dis.dis(bar)
  6           0 LOAD_FAST                0 (x)
              2 LOAD_CONST               1 (1)
              4 INPLACE_ADD
              6 STORE_FAST               0 (x)
              8 LOAD_CONST               0 (None)
             10 RETURN_VALUE

In [13]: dis.dis(foobar)
  9           0 LOAD_GLOBAL              0 (x)
              2 LOAD_CONST               1 (1)
              4 INPLACE_ADD
              6 STORE_GLOBAL             0 (x)
              8 LOAD_CONST               0 (None)
             10 RETURN_VALUE