How to specify __contains__ method?

When I compile the following simple example:

cdef class foo:
 def __contains__(self, key):
   return 1

I get the error message:

d:\msl\gb\python\my\Matrix\bug2.pyx:3:11: Return with value in void function

If I change "def" to "cdef int", it gets past Pyrex but the C compiler 
complains:

bug2.c(147) : warning C4028: formal parameter 1 different from declaration

But it appears to work.

Now in a more complicated case, I can't get it to work properly.

cdef class foo:
 cdef int val
 def __init__(self):
   val = 0

 cdef int __contains__(self, key):
   print 'foo contains', self.val
   return 1

cdef class fee(foo):
 cdef int __contains__(self, key):
   print 'fee contains', self.val
   return 0

cdef class faa(fee):
 def bof(self):
   print 'bof', self.val
 cdef int __contains__(self, key):
   print 'faa contains', self.val
   return 0

If I leave off that last cdef int __contains__, I get C compiler errors like:

bug2.c(275) : warning C4028: formal parameter 1 different from declaration
bug2.c(421) : warning C4028: formal parameter 1 different from declaration
bug2.c(568) : error C2065: 'None' : undeclared identifier
bug2.c(568) : error C2099: initializer is not a constant

With it included, it will compile but when I try to do
import bug2
faa = bug2.faa()
1 in faa

I get:
faa contains
Exception exceptions.AttributeError: "'bug2.faa' object has no 
attribute 'val'" in 'bug2.faa.__contains__' ignored

I seem to have lost my connection (via inheritance) to the original foo class.

I poked around in the Pyrex0.9 source a little but couldn't find my way 
to where this might happen.

Any ideas for a work around?

Thanks for Pyrex, it is GREAT STUFF.
gb