How to use the pint.models.model_builder.get_model function in Pint

def setUpClass(cls):
        os.chdir(datadir)
        cls.parfileB1855 = "B1855+09_NANOGrav_dfg+12_modified_DD.par"
        cls.timB1855 = "B1855+09_NANOGrav_dfg+12.tim"
        cls.toasB1855 = toa.get_TOAs(
            cls.timB1855, ephem="DE405", planets=False, include_bipm=False
        )
        cls.modelB1855 = mb.get_model(cls.parfileB1855)
        # libstempo result
        cls.ltres, cls.ltbindelay = np.genfromtxt(
            cls.parfileB1855 + ".tempo_test", unpack=True
        )

#!/usr/bin/env python
import pint.toa
import pint.models
import pint.fitter
import numpy as np
import pint.residuals
import pint.models.model_builder as mb
import astropy.units as u
import os, sys

from pinttestdata import testdir, datadir

os.chdir(datadir)

# This par file has a very simple model in it
m = mb.get_model('slug.par')

# This .tim file has TOAs at the barycenter, and at infinite frequency
t = pint.toa.get_TOAs('slug.tim')

rs = pint.residuals.Residuals(t, m).time_resids

# Residuals should be less than 2.0 ms
assert rs.std() < 2.0*u.ms

def setUpClass(cls):
        os.chdir(datadir)
        cls.parfileB1855 = "B1855+09_NANOGrav_dfg+12_TAI_FB90.par"
        cls.timB1855 = "B1855+09_NANOGrav_dfg+12.tim"
        try:
            cls.toasB1855 = toa.get_TOAs(
                cls.timB1855, ephem="DE405", planets=False, include_bipm=False
            )
        except IOError:
            pytest.skip("Unable to fetch ephemeris")
        cls.modelB1855 = mb.get_model(cls.parfileB1855)
        logging.debug("%s" % cls.modelB1855.components)
        logging.debug("%s" % cls.modelB1855.params)
        # tempo result
        cls.ltres = np.genfromtxt(
            cls.parfileB1855 + ".tempo2_test", skip_header=1, unpack=True
        )

def setUpClass(self):
        os.chdir(datadir)
        self.parfileB1855 = 'B1855+09_polycos.par'
        self.timB1855 = 'B1855_polyco.tim'
        self.toasB1855 = toa.get_TOAs(self.timB1855, ephem="DE405",
                                      planets=False, include_bipm=False)
        self.modelB1855 = mb.get_model(self.parfileB1855)
        # Read tempo style polycos.
        self.plc = Polycos()
        self.plc.read_polyco_file('B1855_polyco.dat', 'tempo')
    def TestD_phase_d_toa(self):

def setUpClass(self):
        # This uses ELONG and ELAT
        self.m1 = mb.get_model('B1855+09_NANOGrav_9yv1.gls.par')
        # This uses RA and DEC
        self.m2 = mb.get_model('B1855+09_NANOGrav_dfg+12_TAI_FB90.par')
        self.t = 5000 * np.random.randn(100) + 49453.0

def setUpClass(cls):
        os.chdir(datadir)
        cls.parf = "B1855+09_NANOGrav_dfg+12_TAI.par"
        cls.timf = "B1855+09_NANOGrav_dfg+12.tim"
        cls.JUMPm = mb.get_model(cls.parf)
        cls.toas = toa.get_TOAs(
            cls.timf, ephem="DE405", planets=False, include_bipm=False
        )
        # libstempo calculation
        cls.ltres = np.genfromtxt(
            cls.parf + ".tempo_test", unpack=True, names=True, dtype=np.longdouble
        )

def setUpClass(cls):
        os.chdir(datadir)
        cls.m = get_model("B1855+09_NANOGrav_dfg+12_modified.par")
        cls.mp = get_model("prefixtest.par")

def setUpClass(cls):
        os.chdir(datadir)
        cls.parfileB1855 = "B1855+09_NANOGrav_9yv1.gls.par"
        cls.timB1855 = "B1855+09_NANOGrav_9yv1.tim"
        cls.toasB1855 = toa.get_TOAs(
            cls.timB1855, ephem="DE421", planets=False, include_bipm=False
        )
        cls.modelB1855 = mb.get_model(cls.parfileB1855)
        # tempo result
        cls.ltres = np.genfromtxt(
            cls.parfileB1855 + ".tempo2_test", skip_header=1, unpack=True
        )

def setUpClass(cls):
        os.chdir(datadir)
        cls.par = "B1855+09_NANOGrav_9yv1.gls.par"
        cls.tim = "B1855+09_NANOGrav_9yv1.tim"
        cls.m = mb.get_model(cls.par)
        cls.t = toa.get_TOAs(cls.tim, ephem="DE436")
        cls.f = GLSFitter(cls.t, cls.m)
        # get tempo2 parameter dict
        with open("B1855+09_tempo2_gls_pars.json", "r") as fp:
            cls.t2d = json.load(fp)

log.error(
        "This example requires tempo_utils, download from: https://github.com/demorest/tempo_utils and 'pip install .'"
    )
    raise

# Using Nanograv data B1855
datadir = "../../tests/datafile"
parfile = os.path.join(datadir, "B1855+09_NANOGrav_dfg+12_TAI_FB90.par")
timfile = os.path.join(datadir, "B1855+09_NANOGrav_dfg+12.tim")

# libstempo calculation
print("tempo2 calculation")
tempo2_vals = tempo2_utils.general2(parfile, timfile, ["pre"])
# Build PINT model
print("PINT calculation")
mdd = mb.get_model(parfile)
# Get toas to pint
toas = toa.get_TOAs(timfile, planets=False, ephem="DE405", include_bipm=False)
# Get residuals
t2_resids = tempo2_vals["pre"]
presids_us = resids(toas, mdd).time_resids.to(u.us)
# Plot residuals
plt.errorbar(toas.get_mjds().value, presids_us.value, toas.get_errors().value, fmt="x")
print(toas.get_errors().value)
print(toas.get_mjds())

print(presids_us.value)
plt.title("%s Pre-Fit Timing Residuals" % mdd.PSR.value)
plt.xlabel("MJD")
plt.ylabel("Residual (us)")
plt.grid()
plt.show()