You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: pointer.go
    path of file: ./repos/sealer/vendor/github.com/xeipuuv/gojsonpointer
    
    the code of the file until where you have to start completion: // Copyright 2015 xeipuuv ( https://github.com/xeipuuv )
//
// Licensed und
    
func NewJsonPointer(jsonPointerString string) (p JsonPointer, err error) {

	// Pointer to the root of the document
	if len(jsonPointerString) == 0 {
		// Keep referenceTokens nil
		return
	}
	if jsonPointerString[0] != '/' {
		return p, errors.New(const_invalid_start)
	}

	p.referenceTokens = strings.Split(jsonPointerString[1:], const_pointer_separator)
	return
}