def unbind(instance_id, binding_id):
    """
    Unbind an existing instance associated
    with the binding_id provided

    DELETE /v2/service_instances/<instance_id>/service_bindings/<binding_id>:
        <instance_id> is the Cloud Controller provided
          value used to provision the instance
        <binding_id> is the Cloud Controller provided
          value used to bind the instance

    return:
        As of API 2.3, an empty JSON document
        is expected
    """
    print("inside unbinding")
    return {}