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Continue to ChatFourTap - Checking in to Foursquare using an Oyster card https://www.mikelitman.co.uk/2010/05/fourtap-checking-in-to-foursquare-using-an-oyster-card/
FourTap - Checking in to Foursquare using an Oyster card https://www.mikelitman.co.uk/2010/05/fourtap-checking-in-to-foursquare-using-an-oyster-card/