Correct way to get output of run_pty from a boto sshclient

Question

I am trying to execute a remote command on an ec2 instance that needs sudo.

example code snippet

conn = boto.ec2.connect_to_region(....)
instance = conn.get_only_instances(instance_ids=instance_id)[0]
ssh_client = sshclient_from_instance(instance, ssh_key_file='path.to.pem,user_name='ec2-user')
chan = ssh_client.run_pty('sudo ls /root')

Using just ssh_client.run() returns a tuple that was easy to deal with but doesn't allow sudo. run_pty is returning paramiko.channel.Channel and I can use recv() to get some output back but I am not clear how to get the entire stdout.