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