provider/vsphere/vsphere_discover.go
func discoverErr(format string, a ...interface{}) error {
	var s string
	if len(a) > 1 {
		s = fmt.Sprintf(format, a...)
	} else {
		s = format
	}
	return fmt.Errorf("discover-vsphere: %s", s)
}
func discoverErr(format string, a ...interface{}) error {
	var s string
	if len(a) > 1 {
		s = fmt.Sprintf(format, a...)
	} else {
		s = format
	}
	return fmt.Errorf("discover-vsphere: %s", s)
}
// discoverErr prints out a friendly error heading for the top-level discovery
// errors. It should only be used in the Addrs method.