Got solution as below.
Install pyopt library : pip install pyotp
import pyotp
use the topo detail with pyotp as below:
topo = Trading_api_key_details.topo
topt = pyotp.TOTP(topo)
topt = topt.now()
data = obj.generateSession(username,pwd,topt)
refreshToken= data['data']['refreshToken']
print(data)