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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 _orient3dfast(plane, pd):
 """ Performs a fast 3D orientation test. Parameters plane: (3,3) float, three points in space that define a plane pd: (3,) float, a single point Returns ------- result: float, if greater than zero then pd is above the plane through the given three points, if less than zero then pd is below the given plane, and if equal to zero then pd is on the given plane. """

    pa, pb, pc = plane
    adx = pa[0] - pd[0]
    bdx = pb[0] - pd[0]
    cdx = pc[0] - pd[0]
    ady = pa[1] - pd[1]
    bdy = pb[1] - pd[1]
    cdy = pc[1] - pd[1]
    adz = pa[2] - pd[2]
    bdz = pb[2] - pd[2]
    cdz = pc[2] - pd[2]

    return (adx * (bdy * cdz - bdz * cdy)
            + bdx * (cdy * adz - cdz * ady)
            + cdx * (ady * bdz - adz * bdy))