intersection algorithm in python

gistfile1.py

def intersection( *A ) :
    res = []
    while True :
        # check if the heads are the same
        all_same = True
        for i in range(1, len(A)) :
            if len(A[i]) > 0 and len(A[i-1]) > 0 and A[i-1][0] == A[i][0] :
                pass
            else :
                all_same = False        
        if all_same :
            # append to intersection set
            res.append(A[0][0])
            # remove from all arrays the intersected item
            for i in range(len(A)) :
                if len(A[i]) > 0 :
                    tmp = A[i][0]
                    while A[i] != [] and A[i][0] == tmp :
                        A[i].pop(0)
                else :
                    return res
        else :
            # find the array with minimum head ...
            min_i = 0
            for i in range(len(A)) :
                if len(A[i]) == 0 or len(A[min_i]) == 0 :
                    return res
                if A[i][0] < A[min_i][0] :
                    min_i = i
            # and remove it's head item
            A[min_i].pop(0)            

# Example code
A = [1,2,3,4,4.1,4.2,4.3,5,7,8,100]
B = [2,5,7,8]
C = [2,3,4,5,6,7,8]

print intersection( A, B, C )