router/colon.go
func Colon(path string) *colon {
	matches := strings.Split(path, "/")
	return &colon{
		matches: matches,
	}
}
func Colon(path string) *colon {
	matches := strings.Split(path, "/")
	return &colon{
		matches: matches,
	}
}
// Colon matches path with REST-full resources URI in perfix colon form.
// e.g., "/foo/v1/bar/v2" will map to "/:foo/:bar" form,
// while the value of "foo" and "bar" are "v1" and "v2", respectively.