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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 signed_area(coords):

 """Return the signed area enclosed by a ring using the linear time
 algorithm. A value >= 0 indicates a counter-clockwise oriented ring.
 """

    xs, ys = map(list, zip(*coords))
    xs.append(xs[1])
    ys.append(ys[1])
    return sum(xs[i]*(ys[i+1]-ys[i-1]) for i in range(1, len(coords)))/2.0