晋太元中，武陵人捕鱼为业。缘溪行，忘路之远近。忽逢桃花林，夹岸数百步，中无杂树，芳草鲜美，落英缤纷。渔人甚异之，复前行，欲穷其林。 　　林尽水源，便得一山，山有小口，仿佛若有光。便舍船，从口入。初极狭，才通人。复行数十步，豁然开朗。土地平旷，屋舍俨然，有良田、美池、桑竹之属。阡陌交通，鸡犬相闻。其中往来种作，男女衣着，悉如外人。黄发垂髫，并怡然自乐。 　　见渔人，乃大惊，问所从来。具答之。便要还家，设酒杀鸡作食。村中闻有此人，咸来问讯。自云先世避秦时乱，率妻子邑人来此绝境，不复出焉，遂与外人间隔。问今是何世，乃不知有汉，无论魏晋。此人一一为具言所闻，皆叹惋。余人各复延至其家，皆出酒食。停数日，辞去。此中人语云：“不足为外人道也。”(间隔 一作：隔绝) 　　既出，得其船，便扶向路，处处志之。及郡下，诣太守，说如此。太守即遣人随其往，寻向所志，遂迷，不复得路。 　　南阳刘子骥，高尚士也，闻之，欣然规往。未果，寻病终。后遂无问津者。 sh-3ll

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DIR:/lib/node_modules/npm/node_modules/uuid/
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Current File : //lib/node_modules/npm/node_modules/uuid/v1.js
var rng = require('./lib/rng');
var bytesToUuid = require('./lib/bytesToUuid');

// **`v1()` - Generate time-based UUID**
//
// Inspired by https://github.com/LiosK/UUID.js
// and http://docs.python.org/library/uuid.html

var _nodeId;
var _clockseq;

// Previous uuid creation time
var _lastMSecs = 0;
var _lastNSecs = 0;

// See https://github.com/broofa/node-uuid for API details
function v1(options, buf, offset) {
  var i = buf && offset || 0;
  var b = buf || [];

  options = options || {};
  var node = options.node || _nodeId;
  var clockseq = options.clockseq !== undefined ? options.clockseq : _clockseq;

  // node and clockseq need to be initialized to random values if they're not
  // specified.  We do this lazily to minimize issues related to insufficient
  // system entropy.  See #189
  if (node == null || clockseq == null) {
    var seedBytes = rng();
    if (node == null) {
      // Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
      node = _nodeId = [
        seedBytes[0] | 0x01,
        seedBytes[1], seedBytes[2], seedBytes[3], seedBytes[4], seedBytes[5]
      ];
    }
    if (clockseq == null) {
      // Per 4.2.2, randomize (14 bit) clockseq
      clockseq = _clockseq = (seedBytes[6] << 8 | seedBytes[7]) & 0x3fff;
    }
  }

  // UUID timestamps are 100 nano-second units since the Gregorian epoch,
  // (1582-10-15 00:00).  JSNumbers aren't precise enough for this, so
  // time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
  // (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
  var msecs = options.msecs !== undefined ? options.msecs : new Date().getTime();

  // Per 4.2.1.2, use count of uuid's generated during the current clock
  // cycle to simulate higher resolution clock
  var nsecs = options.nsecs !== undefined ? options.nsecs : _lastNSecs + 1;

  // Time since last uuid creation (in msecs)
  var dt = (msecs - _lastMSecs) + (nsecs - _lastNSecs)/10000;

  // Per 4.2.1.2, Bump clockseq on clock regression
  if (dt < 0 && options.clockseq === undefined) {
    clockseq = clockseq + 1 & 0x3fff;
  }

  // Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
  // time interval
  if ((dt < 0 || msecs > _lastMSecs) && options.nsecs === undefined) {
    nsecs = 0;
  }

  // Per 4.2.1.2 Throw error if too many uuids are requested
  if (nsecs >= 10000) {
    throw new Error('uuid.v1(): Can\'t create more than 10M uuids/sec');
  }

  _lastMSecs = msecs;
  _lastNSecs = nsecs;
  _clockseq = clockseq;

  // Per 4.1.4 - Convert from unix epoch to Gregorian epoch
  msecs += 12219292800000;

  // `time_low`
  var tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
  b[i++] = tl >>> 24 & 0xff;
  b[i++] = tl >>> 16 & 0xff;
  b[i++] = tl >>> 8 & 0xff;
  b[i++] = tl & 0xff;

  // `time_mid`
  var tmh = (msecs / 0x100000000 * 10000) & 0xfffffff;
  b[i++] = tmh >>> 8 & 0xff;
  b[i++] = tmh & 0xff;

  // `time_high_and_version`
  b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
  b[i++] = tmh >>> 16 & 0xff;

  // `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
  b[i++] = clockseq >>> 8 | 0x80;

  // `clock_seq_low`
  b[i++] = clockseq & 0xff;

  // `node`
  for (var n = 0; n < 6; ++n) {
    b[i + n] = node[n];
  }

  return buf ? buf : bytesToUuid(b);
}

module.exports = v1;