[{'role': 'user', 'content': "Analyze the following clause from a privacy policy and determine if it's fair or unfair. Also identify any privacy practices mentioned: Marketing or commercial communications: You may unsubscribe from receiving marketing or commercial communications about BlackBerry or BlackBerry® products, services and software by: clicking the unsubscribe link at the end of any marketing or commercial communication from BlackBerry; by indicating your preference at http://www.blackberry.com/unsubscribe; or by writing to BlackBerry Privacy Office c/o BlackBerry (attention Legal Department), 2200 University Avenue East, Waterloo, Ontario, Canada, N2K 0A7 and advising what particular types of marketing or commercial communications you no longer wish to receive."}, {'role': 'assistant', 'content': 'This clause is fair. The privacy practices mentioned are: nan.'}]