Given the source code of a project, please identify all API endpoints defined in the code.
 This code may include files such as controllers, routes, and handlers, which contain logic for processing HTTP requests.
* Input Example:
 ** Code:
 // routes.go
    r.HandleFunc("/books", GetBooksHandler).Methods("GET")
    r.HandleFunc("/books/{id}", GetBookByIDHandler).Methods("GET")
    r.HandleFunc("/books", CreateBookHandler).Methods("POST")
* Output Example:
{
  "api_endpoints": [
    {
      "method": "GET",
      "path": "/books",
      "handler_function": "GetBooksHandler",
    },
    {
      "method": "GET",
      "path": "/books/{id}",
      "handler_function": "GetBookByIDHandler",
    },
    {
      "method": "POST",
      "path": "/books",
      "handler_function": "CreateBookHandler",
    }
  ]
}
or return 'none' if not any api.
with this Input: {Code}, Output (json or 'none')?