code: function is_overflow (x) {
          return (
              ((x[0] > P26 - 19)) &&
                  ((x[1] & x[3] & x[5] & x[7] & x[9]) === P25) &&
                  ((x[2] & x[4] & x[6] & x[8]) === P26)
              ) || (x[9] > P25);
      }
docs: /* Check if reduced-form input >= 2^255-19