<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def pssm_array2pwm_array(arr, background_probs=DEFAULT_BASE_BACKGROUND):
 """Convert pssm array to pwm array """

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