args.go
func (a *Args) GetUint(key string) (int, error) {
	value := a.Peek(key)
	if len(value) == 0 {
		return -1, ErrNoArgValue
	}
	return ParseUint(value)
}
func (a *Args) GetUint(key string) (int, error) {
	value := a.Peek(key)
	if len(value) == 0 {
		return -1, ErrNoArgValue
	}
	return ParseUint(value)
}
// GetUint returns uint value for the given key.