code: function (str) {
                var allPairs = [], pairs;
                var words = str.split(/\s+/);
                for (var i = 0; i < words.length; i++) {
                  pairs = letterPairs(words[i]);
                  allPairs.push.apply(allPairs, pairs);
                }
                return allPairs;
              }
docs: Get all of the pairs in all of the words for a string