To walk through the four steps discussed in class:

1. rec_in(some_list, item)
2. Recusive case: Imagine that you have a working version 
of rec_in, however, you can only call it on smaller versions of
your problem (in this case) a smaller list, how could we 
solve the problem?

Check the first thing in the list to see if it matches 
the item, if it does, return True.  Otherwise, check
the rest of the list with our recursive function.

3. base case: if the list is empty, than the item isn't in the list
4. Put it all together:

def rec_in(some_list, item):
    if len(some_list) == 0:
        return False
    else:
        if some_list[0] == item:
            return True
        else:
            return rec_in(some_list[1:], item)


If you want to get fancy, a shorter version of this is:

def rec_in(some_list, item):
    if len(some_list) == 0:
        return False
    else:
        return some_list[0] == item or rec_in(some_list[1:], item)