Help! I have a problem with lists!

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Hello!

I am a real beginner in Sage, I have just started th use it. In fact this is my first programing language, so I have some difficulties with it... Now I needed a command, which determins all the k-element subset of [1,2,...,N]. Since I don't found a command like this, I decided to write a program... :-) And now I simple don't understand while my program doesn't work corrrectly! Could you explain me? It is a bit longish, so sorry for this.

def eve(A,N):
    """
    the largest elem in the list A which can
    be increased by 1, such that the resulting list contains only 
    different elements less than N. Originally
    A should contain different elements in increasing order.
    """         
    ev = len(A)-1
    while A[ev] == ev+N-len(A):
        ev=ev-1    
    return ev        

def rakovetkezo(A,N):
    """
    Increases the eve(A,N)nt element by 1, and all the other elements 
    after this element are succesive natural numbers
    """
    Q=A
    ev=eve(Q,N)
    x=Q[ev]  
    for i in range(ev,len(Q)):
        Q[i]=x+i-ev+1
    return Q   

def reszhalmazok(N,k):
    """
    It should (but it doesn't) return the k-element 
    subset of [1,2,...,N]
    """
    X=range(k)
    B=[range(k)]
    ev=eve(X,N)
    while ev != -1:
        X=rakovetkezo(X,N)
        B.append(X)
        ev = eve(X,N)
    return B

Now reszhalmazok(5,3) should return [[0,1,2], [0,1,3],...] but it returns something completely different, aaand I don't see why, and how could be improve it?

Katika