remove unused + unexported concat function
remove unused + unexported concat function

admpub/goreq,MeGaPk/goreq,evalphobia/goreq,CrowdSurge/goreq,gcnonato/goreq,vvelikodny/goreq,sschepens/goreq,franela/goreq,ryansb/goreq,dickeyxxx/goreq,appfront/goreq,ProjectFrank/goreq