Устройство интерпретатора языка Python

# File myfun.py
            def fun(s):
              lst = []
              for i in s:
                lst.append(ord(i))
              return lst

>>> import pdb, myfun
            >>> pdb.runcall(myfun.fun, "ABCDE")
            > /examples/myfun.py(4)fun()
            -> lst = []
            (Pdb) n
            > /examples/myfun.py(5)fun()
            -> for i in s:
            (Pdb) n
            > /examples/myfun.py(6)fun()
            -> lst.append(ord(i))
            (Pdb) l
              1     #!/usr/bin/python
              2     # File myfun.py
              3     def fun(s):
              4       lst = []
              5       for i in s:
              6  ->     lst.append(ord(i))
              7       return lst
            [EOF]
            (Pdb) p lst
            []
            (Pdb) p vars()
            {'i': 'A', 's': 'ABCDE', 'lst': []}
            (Pdb) n
            > /examples/myfun.py(5)fun()
            -> for i in s:
            (Pdb) p vars()
            {'i': 'A', 's': 'ABCDE', 'lst': [65]}
            (Pdb) n
            > /examples/myfun.py(6)fun()
            -> lst.append(ord(i))
            (Pdb) n
            > /examples/myfun.py(5)fun()
            -> for i in s:
            (Pdb) p vars()
            {'i': 'B', 's': 'ABCDE', 'lst': [65, 66]}
            (Pdb) r
            - Return -
            > /examples/myfun.py(7)fun()->[65, 66, 67, 68, 69]
            -> return lst
            (Pdb) n
            [65, 66, 67, 68, 69]
            >>>