code: function pickBy(fn, moments) {
          var res, i;
          if (moments.length === 1 && isArray(moments[0])) {
              moments = moments[0];
          }
          if (!moments.length) {
              return moment();
          }
          res = moments[0];
          for (i = 1; i < moments.length; ++i) {
              if (moments[i][fn](res)) {
                  res = moments[i];
              }
          }
          return res;
      }
docs: Pick a moment m from moments so that m[fn](other) is true for all other. This relies on the function fn to be transitive.  moments should either be an array of moment objects or an array, whose first element is an array of moment objects.