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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 _cosine_function(x, a, b, t_shift):
 """genrates a diurnal course of windspeed accroding to the cosine function Args: x: series of euqally distributed windspeed values a: parameter a for the cosine function b: parameter b for the cosine function t_shift: parameter t_shift for the cosine function Returns: series including diurnal course of windspeed. """


    mean_wind, t = x
    return a * mean_wind * np.cos(np.pi * (t - t_shift) / 12) + b * mean_wind