How to use the skyfield.api.load.timescale function in skyfield

if (dbtype == "sqlserver"):
        if dbusername == None:
            try: 
                dbusername = input("Username: ") 
            except Exception as error: 
                log.warning('ERROR: password must be specified {}'.format(error))
        if dbpassword == None:
            try: 
                dbpassword = getpass() 
            except Exception as error: 
                log.warning('ERROR: password must be specified {}'.format(error))

    # Set up database connection
    db = database.Database(dbname,dbtype,dbhostname,dbusername,dbpassword)

    ts = load.timescale()

    # 408821	"2019-08-24 13:38:39"	"leobarhorst@gmail.com"	37162	"2010-046A  "	4172	"E"	"20190824031442326"	"2019-08-24 03:14:42.3260"	0.1	NULL	"2"	"5"	2000	105.828	59.80349999999999	0	0	0.30000000000000004	"S"	NULL	NULL	NULL	NULL	NULL	NULL	"IOD"	"37162 10 046A   4172 E 20190824031442326 17 25 0703312+594821 37 S"	1	NULL	"370139ccab6591ba36c6fc2c33081a76"	"2019-08-25 17:44:27"
    # 408820	"2019-08-24 13:38:39"	"leobarhorst@gmail.com"	37162	"2010-046A  "	4172	"E"	"20190824031438341"	"2019-08-24 03:14:38.3410"	0.1	NULL	"2"	"5"	2000	106.752	58.856833333333334	0	0	0.30000000000000004	"S"	NULL	NULL	NULL	NULL	NULL	NULL	"IOD"	"37162 10 046A   4172 E 20190824031438341 17 25 0707008+585141 37 S"	1	NULL	"c24602b9fd0d66538baa8256813ec371"	"2019-08-25 17:44:26"
    # 408819	"2019-08-24 13:38:39"	"leobarhorst@gmail.com"	37162	"2010-046A  "	4172	"E"	"20190824031434357"	"2019-08-24 03:14:34.3570"	0.1	NULL	"2"	"5"	2000	107.57825	57.9475	0	0	0.30000000000000004	"S"	NULL	NULL	NULL	NULL	NULL	NULL	"IOD"	"37162 10 046A   4172 E 20190824031434357 17 25 0710313+575685 37 S"	1	NULL	"9a097ee7bb889d01b0eb43452018e510"	"2019-08-25 17:44:26"

    # For Alt/Az conversions
    planets = load('de421.bsp')
    earth = planets['earth']
    # iod_obs_id = input("IOD db ID: ")
    while(True):
        try:
            iod_obs_id = input("\nEnter 3 IOD Obs IDs: ")
            iod_obs_id = iod_obs_id.strip()
            iod_obs = iod_obs_id.split(' ')
        except:
            break

from skyfield import api
from skyfield.api import load
from skyfield.constants import tau
from skyfield.data.mpc import COMET_URL, load_comets_dataframe

with load.open(COMET_URL) as f:
    df = load_comets_dataframe(f)

from skyfield.keplerlib import KeplerOrbit

ts = load.timescale(builtin=True)

from numpy import sqrt

df['semimajor_axis_au'] = (
    df['perihelion_distance_au'] / (1.0 - df['eccentricity'])
)

from skyfield.data.gravitational_parameters import GM_dict
from skyfield.constants import AU_KM, DAY_S

mu_km3_s2 = GM_dict[10]
mu_au3_d2 = mu_km3_s2 / (AU_KM**3.0) * (DAY_S**2.0)

row = df.ix[0]

t_perihelion = ts.tt(

def main():

	#planets = load('de421.bsp')
	#earth = planets['earth']

	Site = CosparSite("data/sites.txt")
	duvall = Topos('47.77166666666667 N', '121.90416666666667 W')



	ts = load.timescale()

	#t = ts.now()

	#stations_url = 'http://celestrak.com/NORAD/elements/stations.txt'
	satellites_file = '../tle/bulk.tle'
	satellites = load.tle(satellites_file)

	#satellite = satellites['ARKYD 6A']
	satellite = satellites['TDRS 11']


	#astrometric = observer_location.at(t).observe(mars)
	#alt, az, d = astrometric.apparent().altaz()

	#print(" AZ: ",az)
	#print("ALT: ",alt)

def compute(target, kernel=de421, name=None, topo=None, t=None, planet=0,
            precision_radec=15, precision_azalt=120, klass=None, json=None):
    ts = sf.load.timescale()
    if isinstance(target, str):
        name = target
        target = kernel[target]

    if topo is None:
        topo = ['33.7490 N', '84.3880 W'] # Atlanta.
    topo = sf.Topos(*topo)

    if t is None:
        t = [2019, 9, 6, 17, 0, 0]
    t = ts.utc(*t)
    if name is None:
        name = target.target_name
    if not planet and isinstance(target.target, int):
        planet = target.target