create tracker using python code

Software Natron
1

import os
import NatronEngine
from NatronGui import *

index = 0
app = natron.getInstance(index)
reader = app.createReader(“C:/Users/Kosala Chamikara/Downloads/Video/Narcos.Mexico.S02E04.720p.DreamMovie.mkv”)
tracker=app.createNode(“fr.inria.built-in.Tracker”)
viewer=app.createNode(“fr.inria.built-in.Viewer”)
viewer.connectInput(0,tracker)
tracker.connectInput(0,reader)

this is the code i have.this lines can create the tracer nodes. but, it cant create tracker points.
someone please help me.

track1=app.tracker.createTrack()
i have tried this code also. but it gives me this error.
natronengine.App object has no attribute tracker