def select_roi(cur, roi_id):
    """Selects an ROI from the ID.
    
    Args:
        cur: Connection's cursor.
        roi_id: The ID of the ROI.
    
    Returns:
        The ROI.
    """
    cur.execute("SELECT * FROM rois WHERE id = ?", (roi_id, ))
    row = cur.fetchone()
    return row