Pair is a smart-contract responsible for opening, closing and liquidating trading positions. Pair contracts are created for each tradable/lendable token pair, for example, CAKE-BNB. Pair contracts temporary hold all tradable tokens bought by traders, and mint proxy-tokens, which are sent to traders instead of real tokens. Proxy-tokens are necessary to make sure that traders pay back their debts to the liquidity pools. Proxy-tokens are pegged 1:1 to real tokens held by Pair contracts on behalf of traders.