@staticmethod
def is_file_modified(old_file_meta, file_meta):
    """Check for changes on inode or file data

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