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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 geo_point_n(arg, n):
 """Return the Nth point in a single linestring in the geometry. Negative values are counted backwards from the end of the LineString, so that -1 is the last point. Returns NULL if there is no linestring in the geometry Parameters arg : geometry n : integer Returns ------- PointN : geometry scalar """

    op = ops.GeoPointN(arg, n)
    return op.to_expr()