I thought I had a pretty good handle on Python internals, until some time early this year when I took an interest in the generated bytecode. I'd read plenty of the cpython source, written lots of cython extensions, etc., but somehow missed the middle piece.

Fortunately, it's really easy to get at the bytecode, and quite instructive. Random inquiry: how do generator functions work?

  In [1]: def foo(): 
     ...:     yield from range(10) 
     ...:                                                                                                                                                                                                            

  In [2]: import dis                                                                                                                                                                                                 

  In [3]: dis.dis(foo)                                                                                                                                                                                               
    2           0 LOAD_GLOBAL              0 (range)
                2 LOAD_CONST               1 (10)
                4 CALL_FUNCTION            1
                6 GET_YIELD_FROM_ITER
                8 LOAD_CONST               0 (None)
               10 YIELD_FROM
               12 POP_TOP
               14 LOAD_CONST
               16 RETURN_VALUE

From there, you can read how each of those bytecode instructions is implemented in ceval.c, which formerly_proven links to.

edit: probably nice to have the actual disassembly of a list comprehension, too:

  In [4]: def bar(): 
     ...:     return [x for x in range(10)] 
     ...:                                                                                                                                                                                                            
  
  In [5]: dis.dis(bar)                                                                                                                                                                                               
    2           0 LOAD_CONST               1 (<code object <listcomp> at 0x7f814059f450, file "<ipython-input-4-a7a3cc7e7d7f>", line 2>)
                2 LOAD_CONST               2 ('bar.<locals>.<listcomp>')
                4 MAKE_FUNCTION            0
                6 LOAD_GLOBAL              0 (range)
                8 LOAD_CONST               3 (10)
               10 CALL_FUNCTION            1
               12 GET_ITER
               14 CALL_FUNCTION            1
               16 RETURN_VALUE
  
  Disassembly of <code object <listcomp> at 0x7f814059f450, file "<ipython-input-4-a7a3cc7e7d7f>", line 2>:
    2           0 BUILD_LIST               0
                2 LOAD_FAST                0 (.0)
          >>    4 FOR_ITER                 8 (to 14)
                6 STORE_FAST               1 (x)
                8 LOAD_FAST                1 (x)
               10 LIST_APPEND              2
               12 JUMP_ABSOLUTE            4
          >>   14 RETURN_VALUE