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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 _arcball(xy, wh):
 """Convert x,y coordinates to w,x,y,z Quaternion parameters Adapted from: linalg library Copyright (c) 2010-2015, Renaud Blanch <rndblnch at gmail dot com> Licence at your convenience: GPLv3 or higher <http://www.gnu.org/licenses/gpl.html> BSD new <http://opensource.org/licenses/BSD-3-Clause> """

    x, y = xy
    w, h = wh
    r = (w + h) / 2.
    x, y = -(2. * x - w) / r, (2. * y - h) / r
    h = np.sqrt(x*x + y*y)
    return (0., x/h, y/h, 0.) if h > 1. else (0., x, y, np.sqrt(1. - h*h))