How to use the s3contents.genericfs.GenericFSError function in s3contents

"""
        Build a file model from database record.
        """
        model = base_model(path)
        model["type"] = "file"
        if self.fs.isfile(path):
            model["last_modified"] = model["created"] = self.fs.lstat(path)["ST_MTIME"]
        else:
            model["last_modified"] = model["created"] = DUMMY_CREATED_DATE
        if content:
            try:
                # Get updated format from fs.read()
                content, format_ = self.fs.read(path, format)
            except NoSuchFile as e:
                self.no_such_entity(e.path)
            except GenericFSError as e:
                self.do_error(str(e), 500)
            model["format"] = format_
            model["content"] = content
            model["mimetype"] = mimetypes.guess_type(path)[0] or "text/plain"
        return model

def lstat(self, path):
        raise NotImplementedError(
            "Should be implemented by the file system abstraction"
        )

    def write(self, path, content, format):
        raise NotImplementedError(
            "Should be implemented by the file system abstraction"
        )


class GenericFSError(Exception):
    pass


class NoSuchFile(GenericFSError):
    def __init__(self, path, *args, **kwargs):
        self.path = path
        self.message = "No such file or directory: {}".format(path)
        super(NoSuchFile, self).__init__(self.message, *args, **kwargs)