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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 _deriv_arctan2(y, x):
 """Derivative of the arctan2 function"""

    r2 = x*x + y*y
    df_dy = x / r2
    df_dx = -y / r2
    return np.hstack([df_dy, df_dx])