'Attach this ENI to an EC2 instance.
:type instance_id: str
:param instance_id: The ID of the EC2 instance to which it will
be attached.
:type device_index: int
:param device_index: The interface nunber, N, on the instance (eg. ethN)
:rtype: bool
:return: True if successful'

def attach(self, instance_id, device_index, dry_run=False):

    return self.connection.attach_network_interface(self.id, instance_id, device_index, dry_run=dry_run)
