How to use the skypy.current_task function in skypy

def wait(self, **kwargs):
        out_dict = {"id": self.ref.id}
        out_dict.update(kwargs)
        runtime_response = skypy.current_task.message_helper.synchronous_request("wait_stream", out_dict)
        if not runtime_response["success"]:
            raise Exception("File transfer failed before EOF")
        else:
            self.really_eof = runtime_response["done"]
            self.current_size = runtime_response["size"]

}
                               )
                write_framed_json(out_message, write_fp)
            elif skypy.current_task.halt_reason == skypy.HALT_DONE:
                out_fp = MaybeFile(open_callback=lambda: skypy.open_output(0))
                with out_fp:
                    if skypy.current_task.persistent_state.export_json:
                        simplejson.dump(skypy.current_task.script_return_val, out_fp)
                    else:
                        pickle.dump(skypy.current_task.script_return_val, out_fp)
                skypy.ref_from_maybe_file(out_fp, 0)
            out_message = ("exit", {"keep_process": "may_keep", "soft_cache_keys": soft_cache.get_cache_keys()})
        write_framed_json(out_message, write_fp)
        if skypy.current_task.halt_reason == skypy.HALT_RUNTIME_EXCEPTION:
            sys.exit(0)
        skypy.current_task = None
    except ShutdownException, e:
        print >>sys.stderr, "SkyPy: killed by Ciel (reason: '%s')" % e.reason
        sys.exit(0)
    except Exception, e:
        print >>sys.stderr, "SkyPy: exception reached top level!"
        report = "Top-level exception %s\n%s" % (repr(e), traceback.format_exc())
        out_message = ("error", {"report": report})
        write_framed_json(out_message, write_fp)
        sys.exit(1)