[Tutor] help with a recursive function

[c smith]

hi list,
i understand the general idea of recursion and if I am following well
written code I can understand how it works, but when I try to write it for
myself I get a bit confused with the flow.
I was trying to turn an ackerman function into python code for practice and
I tried writing it like this:
#!/usr/bin/env python

import sys, os
def ack(m,n):

    if m == 0:
        return n+1
    elif m > 0 and n == 0:
        ack(m-1,1)
    elif m > 0 and n > 0:
        ack(m-1,ack(m,n-1))

if __name__=='__main__':
    sys.argv[1] = int(sys.argv[1])
    sys.argv[2] = int(sys.argv[2])

    print ack(sys.argv[1], sys.argv[2])

The major problem, I think, is that I cant figure out where to turn the args
into ints.
When run in this form I get the 'typeError' error on 'n+1' I guess because
the args are still strings.
Also, does the second 'elif' make sense?
I am not sure if the function can take itself as an argument.
thanks for any suggestions, this list has been a big help.
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