Even the last

def checkio(array):
    """
        sums even-indexes elements and multiply at the last
    """
    i=1
    b=0
    summa=0
    while i!=(len(array)+1):
        if i%2==0:
            b+=array[i-1]
        i+=1
    summa=b*(array[len(array)-1])
    return summa