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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 _correct_for_light_travel_time(observer, target):
 """Return a light-time corrected astrometric position and velocity. Given an `observer` that is a `Barycentric` position somewhere in the solar system, compute where in the sky they will see the body `target`, by computing the light-time between them and figuring out where `target` was back when the light was leaving it that is now reaching the eyes or instruments of the `observer`. """

    t = observer.t
    ts = t.ts
    cposition = observer.position.au
    cvelocity = observer.velocity.au_per_d
    tposition, tvelocity, gcrs_position, message = target._at(t)
    distance = length_of(tposition - cposition)
    light_time0 = 0.0
    t_tdb = t.tdb
    for i in range(10):
        light_time = distance / C_AUDAY
        delta = light_time - light_time0
        if -1e-12 < min(delta) and max(delta) < 1e-12:
            break
        t2 = ts.tdb(jd=t_tdb - light_time)
        tposition, tvelocity, gcrs_position, message = target._at(t2)
        distance = length_of(tposition - cposition)
        light_time0 = light_time
    else:
        raise ValueError('light-travel time failed to converge')
    return tposition - cposition, tvelocity - cvelocity, t, light_time