code: func RegisterMethod(method string) {
  	if method == "" {
  		return
  	}
  	method = strings.ToUpper(method)
  	if _, ok := methodMap[method]; ok {
  		return
  	}
  	n := len(methodMap)
  	if n > strconv.IntSize {
  		panic(fmt.Sprintf("chi: max number of methods reached (%d)", strconv.IntSize))
  	}
  	mt := methodTyp(math.Exp2(float64(n)))
  	methodMap[method] = mt
  	mALL |= mt
  }
docs: // RegisterMethod adds support for custom HTTP method handlers, available
  // via Router#Method and Router#MethodFunc