python - Twisted exception when using ReturnValue -

i`ve got exception when using returnvalue in function

@inlinecallbacks     def my_func(id):   yield somefunc(id)  @inlinecallbacks def somefunc(id):   somevar = yield func(id)    returnvalue(somevar)    returnvalue(somevar) file "/usr/lib64/python2.7/site-packages/twisted/internet/defer.py", line 1105, in returnvalue raise _defgen_return(val) twisted.internet.defer._defgen_return: 

the function works fine, raises exception. how can avoid exception? need return value function.

returnvalue uses exception trick return value/s. normal, exception not cause error.

detail: @inlinecallback decorator looks like

def decorator(...)    try:        .... (func call & other logics)    except exception myexcept:        return myexcept.values