code: func (m *Method) FinalFunc(f FinalFunc) *Method {
  	m.finalFuncs = append(m.finalFuncs, f)
  	return m
  }
docs: // FinalFunc registers a function that is always called as a last one
  // after pre-, handler and post- functions for the given method.
  //
  // It receives a result and an error from last handler that
  // got executed prior to calling final func.