def is_valid_key(key: str) -> bool:
    """Check if an exiftool key is valid and interesting."""
    # https://exiftool.org/TagNames/Extra.html
    file_keys = (
        'FileName', 'Directory', 'FileSize', 'FileModifyDate', 'FileAccessDate',
        'FileInodeChangeDate', 'FilePermissions', 'FileType', 'FileType',
        'FileTypeExtension', 'MIMEType', 'ExifByteOrder'
    )
    invalid_prefixes = ("ExifTool", "System", "SourceFile") + tuple(
        f"File:{k}" for k in file_keys
    )
    for invalid_prefix in invalid_prefixes:
        if key.startswith(invalid_prefix):
            return False

    return True