code: func isWildcard(key string) (bool, string, string) {
  	if key[0] == ':' {
  		substrs := strings.SplitN(key[1:], ":", 2)
  		if len(substrs) == 1 {
  			return true, substrs[0], ""
  		}
  
  		return true, substrs[0], substrs[1]
  	}
  
  	return false, "", ""
  }
docs: // key is a non-empty path segment like "admin" or ":category_id" or ":category_id:\d+"
  // Returns true if it's a wildcard, and if it is, also returns it's name / regexp.
  // Eg, (true, "category_id", "\d+")