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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 uv_at_xy(self, x, y, x0, y0, s0):
 """Returns two arrays of u, v"""

        dx, dy = self.distance(x0, y0, x, y)
        #print 'dx, dy:', dx, dy
        rr2 = (dx**2 + dy**2)**-1
        u = - s0 * dy * r_twopi * rr2
        v = s0 * dx * r_twopi * rr2
        #print 'u, v', u, v
        return u, v