Add an example for the ``_main_for_service`` API.
Add an example for the ``_main_for_service`` API.

moypray/flocker,LaynePeng/flocker,achanda/flocker,wallnerryan/flocker-profiles,jml/flocker,AndyHuu/flocker,jml/flocker,wallnerryan/flocker-profiles,hackday-profilers/flocker,runcom/flocker,achanda/flocker,adamtheturtle/flocker,AndyHuu/flocker,hackday-profilers/flocker,Azulinho/flocker,AndyHuu/flocker,Azulinho/flocker,lukemarsden/flocker,hackday-profilers/flocker,LaynePeng/flocker,mbrukman/flocker,agonzalezro/flocker,w4ngyi/flocker,achanda/flocker,jml/flocker,w4ngyi/flocker,agonzalezro/flocker,LaynePeng/flocker,lukemarsden/flocker,w4ngyi/flocker,Azulinho/flocker,1d4Nf6/flocker,1d4Nf6/flocker,moypray/flocker,adamtheturtle/flocker,mbrukman/flocker,1d4Nf6/flocker,mbrukman/flocker,runcom/flocker,wallnerryan/flocker-profiles,lukemarsden/flocker,runcom/flocker,moypray/flocker,agonzalezro/flocker,adamtheturtle/flocker