code: func IndexJSON(path string) func(a, b string) bool {
  	return func(a, b string) bool {
  		return gjson.Get(a, path).Less(gjson.Get(b, path), false)
  	}
  }
docs: // IndexJSON provides for the ability to create an index on any JSON field.
  // When the field is a string, the comparison will be case-insensitive.
  // It returns a helper function used by CreateIndex.