Demo of the dis module

ipython

In [1]: import dis

In [2]: def foo(what):
   ...:     a = []
   ...:     a = a+4
   ...:     print a[0]
   ...:     b = what[1:4]
   ...:     print b[-1]
   ...:

In [3]: dis.dis(foo)
  2           0 BUILD_LIST               0
              3 STORE_FAST               1 (a)

  3           6 LOAD_FAST                1 (a)
              9 LOAD_CONST               1 (4)
             12 BINARY_ADD
             13 STORE_FAST               1 (a)

  4          16 LOAD_FAST                1 (a)
             19 LOAD_CONST               2 (0)
             22 BINARY_SUBSCR
             23 PRINT_ITEM
             24 PRINT_NEWLINE

  5          25 LOAD_FAST                0 (what)
             28 LOAD_CONST               3 (1)
             31 LOAD_CONST               1 (4)
             34 SLICE+3
             35 STORE_FAST               2 (b)

  6          38 LOAD_FAST                2 (b)
             41 LOAD_CONST               4 (-1)
             44 BINARY_SUBSCR
             45 PRINT_ITEM
             46 PRINT_NEWLINE
             47 LOAD_CONST               0 (None)
             50 RETURN_VALUE

In [4]: