have polymorphic_union render the 'literal' in a type-specific way
have polymorphic_union render the 'literal' in a type-specific way

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