EDINBURGH, UNITED KINGDOM - MAY 03: First Minister and leader of the SNP Nicola Sturgeon and Scottish Liberal Democrat leader Willie Rennie attend the final BBC election debate at Mansfield Traquair on, May 3, 2015 in Edinburgh, Scotland. With just four days to go until polling day in the UK general election Scotlands four main party leaders take part in a live televised debate.. (Photo by Jeff J Mitchell/Getty Images)