<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def nextStationJD(ID, jd):
 """ Finds the aproximate julian date of the next station of a planet. """

    speed = swe.sweObject(ID, jd)['lonspeed']
    for i in range(2000):
        nextjd = jd + i / 2
        nextspeed = swe.sweObject(ID, nextjd)['lonspeed']
        if speed * nextspeed <= 0:
            return nextjd
    return None