code: function toHex(binary, start, end) {
    var hex = "";
    if (end === undefined) {
      end = binary.length;
      if (start === undefined) start = 0;
    }
    for (var i = start; i < end; i++) {
      var byte = binary[i];
      hex += String.fromCharCode(nibbleToCode(byte >> 4)) +
             String.fromCharCode(nibbleToCode(byte & 0xf));
    }
    return hex;
  }
docs: Like slice, but encode as a hex string