def other_types_on_host(host_state, instance_type_id):
    """Tests for overlap between a host_state's instances and an
    instance_type_id.

    Returns True if there are any instances in the host_state whose
    instance_type_id is different than the supplied instance_type_id value.
    """
    host_instances = host_state.instances.values()
    host_types = set([inst.instance_type_id for inst in host_instances])
    inst_set = set([instance_type_id])
    return bool(host_types - inst_set)