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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def auc_roc_score(input:Tensor, targ:Tensor):
    "Using trapezoid method to calculate the area under roc curve"
    fpr, tpr = roc_curve(input, targ)
    d = fpr[1:] - fpr[:-1]
    sl1, sl2 = [slice(None)], [slice(None)]
    sl1[-1], sl2[-1] = slice(1, None), slice(None, -1)
    return (d * (tpr[tuple(sl1)] + tpr[tuple(sl2)]) / 2.).sum(-1)