Connect remote PostgreSQL server through SSH tunnel using python

I am trying to connect remote PostgreSQL using below code with no luck. Need to unblock me here:

from sshtunnel import SSHTunnelForwarder #Run pip install sshtunnel
from sqlalchemy.orm import sessionmaker #Run pip install sqlalchemy
from sqlalchemy import create_engine

with SSHTunnelForwarder(
('<remote server ip>', 22), #Remote server IP and SSH port
ssh_username = "<username>",
ssh_password = "<password>",
remote_bind_address=('<local server ip>', 5432)) as server: #PostgreSQL server IP and sever port on remote machine

server.start() #start ssh sever
print 'Server connected via SSH'

#connect to PostgreSQL
local_port = str(server.local_bind_port)
engine = create_engine('postgresql://<username>:<password>@127.0.0.1:' + local_port +'/database_name')

Session = sessionmaker(bind=engine)
session = Session()

print 'Database session created'

#test data retrieval
test = session.execute("SELECT * FROM database_table")
for row in test:
print row['id']

session.close()