Create and return a new Session Token based on the contents
        of a previously saved JSON-format file.

        :type file_path: str
        :param file_path: The fully qualified path to the JSON-format
            file containing the previously saved Session Token information.

def load(cls, file_path):
        """
        Create and return a new Session Token based on the contents
        of a previously saved JSON-format file.

        :type file_path: str
        :param file_path: The fully qualified path to the JSON-format
            file containing the previously saved Session Token information.
        """
        fp = open(file_path)
        json_doc = fp.read()
        fp.close()
        return cls.from_json(json_doc)