<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def speed_difference(points):
 """ Computes the speed difference between each adjacent point Args: points (:obj:`Point`) Returns: :obj:`list` of int: Indexes of changepoints """

    data = [0]
    for before, after in pairwise(points):
        data.append(before.vel - after.vel)
    return data