code: function int128le_to_hex(a, b, c, d) {
          var ra = ""
          var t = 0
          var ta = 0
          for (var i = 3; i >= 0; i--) {
              ta = arguments[i]
              t = (ta & 0xFF)
              ta = ta >>> 8
              t = t << 8
              t = t | (ta & 0xFF)
              ta = ta >>> 8
              t = t << 8
              t = t | (ta & 0xFF)
              ta = ta >>> 8
              t = t << 8
              t = t | ta
              ra = ra + to_zerofilled_hex(t)
          }
          return ra
      }
docs: convert the 4 32-bit buffers to a 128 bit hex string. (Little-endian is assumed)