added a test to ensure the concrete example in the docs works
added a test to ensure the concrete example in the docs works

276361270/sqlalchemy,alex/sqlalchemy,robin900/sqlalchemy,epa/sqlalchemy,dstufft/sqlalchemy,brianv0/sqlalchemy,inspirehep/sqlalchemy,zzzeek/sqlalchemy,halfcrazy/sqlalchemy,olemis/sqlalchemy,itkovian/sqlalchemy,WinterNis/sqlalchemy,WinterNis/sqlalchemy,sqlalchemy/sqlalchemy,276361270/sqlalchemy,epa/sqlalchemy,wfxiang08/sqlalchemy,pdufour/sqlalchemy,davidfraser/sqlalchemy,EvaSDK/sqlalchemy,bdupharm/sqlalchemy,pdufour/sqlalchemy,wfxiang08/sqlalchemy,j5int/sqlalchemy,elelianghh/sqlalchemy,alex/sqlalchemy,graingert/sqlalchemy,EvaSDK/sqlalchemy,olemis/sqlalchemy,Cito/sqlalchemy,halfcrazy/sqlalchemy,Cito/sqlalchemy,robin900/sqlalchemy,brianv0/sqlalchemy,itkovian/sqlalchemy,davidfraser/sqlalchemy,davidjb/sqlalchemy,monetate/sqlalchemy,j5int/sqlalchemy,bootandy/sqlalchemy,davidjb/sqlalchemy,monetate/sqlalchemy,Akrog/sqlalchemy,alex/sqlalchemy,wujuguang/sqlalchemy,graingert/sqlalchemy,ThiefMaster/sqlalchemy,dstufft/sqlalchemy,wujuguang/sqlalchemy,inspirehep/sqlalchemy,hsum/sqlalchemy,sandan/sqlalchemy,hsum/sqlalchemy,Cito/sqlalchemy,ThiefMaster/sqlalchemy,bdupharm/sqlalchemy,elelianghh/sqlalchemy,sandan/sqlalchemy,bootandy/sqlalchemy,Akrog/sqlalchemy