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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 pwm_array2pssm_array(arr, background_probs=DEFAULT_BASE_BACKGROUND):
 """Convert pwm array to pssm array """

    b = background_probs2array(background_probs)
    b = b.reshape([1, 4, 1])
    return np.log(arr / b).astype(arr.dtype)