Function: vc-call-backend

Call for BACKEND the implementation of FUNCTION-NAME with the given ARGS.
Calls

(apply 'vc-BACKEND-FUN ARGS)

if vc-BACKEND-FUN exists (after trying to find it in vc-BACKEND.el)
and else calls

(apply 'vc-default-FUN BACKEND ARGS)

It is usually called via the `vc-call' macro.