args    *types.Var
	callers []printfCaller
	failed  bool // if true, not a printf wrapper
}

type printfCaller struct {
	w    *printfWrapper
	call *ast.CallExpr
}

// maybePrintfWrapper decides whether decl (a declared function) may be a wrapper
// around a fmt.Printf or fmt.Print function. If so it returns a printfWrapper
// function describing the declaration. Later processing will analyze the