func ParseVersion(vs string) (Version, error) {
	i := strings.IndexByte(vs, '-')
	if i >= 0 {
		vs = vs[:i]
	}
	cstrs := strings.Split(vs, ".")
	v := make(Version, len(cstrs))
	for i, cstr := range cstrs {
		cn, err := strconv.Atoi(cstr)
		if err != nil {
			return nil, fmt.Errorf("could not parse version string: %q is not an integer", cstr)
		}
		if cn < 0 {
			return nil, fmt.Errorf("could not parse version string: %q is negative", cstr)
		}
		v[i] = cn
	}
	return v, nil
}
func ParseVersion(vs string) (Version, error) {
	i := strings.IndexByte(vs, '-')
	if i >= 0 {
		vs = vs[:i]
	}
	cstrs := strings.Split(vs, ".")
	v := make(Version, len(cstrs))
	for i, cstr := range cstrs {
		cn, err := strconv.Atoi(cstr)
		if err != nil {
			return nil, fmt.Errorf("could not parse version string: %q is not an integer", cstr)
		}
		if cn < 0 {
			return nil, fmt.Errorf("could not parse version string: %q is negative", cstr)
		}
		v[i] = cn
	}
	return v, nil
}
// ParseVersion parses a version of the form "12.34.56-abcd". Non-negative
// integer components are separated by dots. An arbitrary suffix may appear
// after '-', which is ignored.