def detect_entry_fold(entry, folds):
    """Detect entry fold.

    Args:
        entry (str): Entry string
        folds (int): Number of folds

    Returns:
        int: Entry fold index
    """
    entry_id = entry.split("[")[0]
    for i in range(len(folds)):
        if entry_id in folds[i]:
            return i
    return None