func Runf(format string, args ...interface{}) ([]byte, error) {
	return Run(fmt.Sprintf(format, args...))
}
func Runf(format string, args ...interface{}) ([]byte, error) {
	return Run(fmt.Sprintf(format, args...))
}
// Runf is like Run, but formats its arguments according to the format.
// Analogous to Printf().