Add docstring for performers.
Add docstring for performers.

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