@staticmethod
def _is_file_modified(old_inode, inode):
    """Check for changes on inode or file data

        :param old_inode: meta data of the previous backup execution
        :param inode: meta data of the current backup execution
        :return: True if the file changed, False otherwise
        """
    file_change_flag = None
    if old_inode['mtime'] != inode['mtime']:
        file_change_flag = True
    elif old_inode['ctime'] != inode['ctime']:
        file_change_flag = True
    return file_change_flag
