klim@moose:~> python 
Python 2.5.2 (r252:60911, Mar  1 2008, 13:52:45) 
[GCC 4.2.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def innerif(a, b, l):
...     if a in l : 
...         if b in l :
...             print a, b, " both in ", l
...         else:
...             print a, " but not ", b, " in ", l
... 
>>> def outerif(a, b, l):
...     if a in l : 
...         if b in l :
...             print a, b, " both in ", l
...     else:
...         print a, " not in ", l
... 
>>> 
>>> innerif(3, 5, [1,2,3,4,5])
3 5  both in  [1, 2, 3, 4, 5]
>>> innerif(3, 6, [1,2,3,4,5])
3  but not  6  in  [1, 2, 3, 4, 5]
>>> innerif(77, 6, [1,2,3,4,5])
>>> 
>>> 
>>> outerif(3, 5, [1,2,3,4,5])
3 5  both in  [1, 2, 3, 4, 5]
>>> outerif(3, 6, [1,2,3,4,5])
>>> outerif(77, 6, [1,2,3,4,5])
77  not in  [1, 2, 3, 4, 5]
>>> 
klim@moose:~>