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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 pyephem(time, latitude, longitude, altitude=0, pressure=101325, temperature=12, horizon='+0:00'):
 """ Calculate the solar position using the PyEphem package. Parameters time : pandas.DatetimeIndex Localized or UTC. latitude : float positive is north of 0 longitude : float positive is east of 0 altitude : float, default 0 distance above sea level in meters. pressure : int or float, optional, default 101325 air pressure in Pascals. temperature : int or float, optional, default 12 air temperature in degrees C. horizon : string, optional, default '+0:00' arc degrees:arc minutes from geometrical horizon for sunrise and sunset, e.g., horizon='+0:00' to use sun center crossing the geometrical horizon to define sunrise and sunset, horizon='-0:34' for when the sun's upper edge crosses the geometrical horizon Returns ------- pandas.DataFrame index is the same as input `time` argument The DataFrame will have the following columns: apparent_elevation, elevation, apparent_azimuth, azimuth, apparent_zenith, zenith. See also -------- spa_python, spa_c, ephemeris """


    # Written by Will Holmgren (@wholmgren), University of Arizona, 2014
    try:
        import ephem
    except ImportError:
        raise ImportError('PyEphem must be installed')

    # if localized, convert to UTC. otherwise, assume UTC.
    try:
        time_utc = time.tz_convert('UTC')
    except TypeError:
        time_utc = time

    sun_coords = pd.DataFrame(index=time)

    obs, sun = _ephem_setup(latitude, longitude, altitude,
                            pressure, temperature, horizon)

    # make and fill lists of the sun's altitude and azimuth
    # this is the pressure and temperature corrected apparent alt/az.
    alts = []
    azis = []
    for thetime in time_utc:
        obs.date = ephem.Date(thetime)
        sun.compute(obs)
        alts.append(sun.alt)
        azis.append(sun.az)

    sun_coords['apparent_elevation'] = alts
    sun_coords['apparent_azimuth'] = azis

    # redo it for p=0 to get no atmosphere alt/az
    obs.pressure = 0
    alts = []
    azis = []
    for thetime in time_utc:
        obs.date = ephem.Date(thetime)
        sun.compute(obs)
        alts.append(sun.alt)
        azis.append(sun.az)

    sun_coords['elevation'] = alts
    sun_coords['azimuth'] = azis

    # convert to degrees. add zenith
    sun_coords = np.rad2deg(sun_coords)
    sun_coords['apparent_zenith'] = 90 - sun_coords['apparent_elevation']
    sun_coords['zenith'] = 90 - sun_coords['elevation']

    return sun_coords