code: function setDefaults() {
      // sequence: generate a random 3-byte integer initial value for the sequence counter
      if (seq === undefined)
          seq = ~~(Math.random() * 0xffffff)
  
      // processId: 2-byte integer derived from the PID assigned by the OS
      if (pid === undefined)
          pid = process.pid % 0xffff
  
      // machineId: first three bytes of the md5 hash calculated from OS hostname
      if (mid === undefined)
          mid = crypto.createHash('md5')
                      .update(os.hostname())
                      .digest()
                      .slice(0, 3)
                      .readUIntBE(0, 3)
  
      // reset the counter
      // (if `mid` or `pid` changes then previously allocated ids in the current second are freed)
      ctr = 0
  
      // `unique` is the fixed-length composition of `mid` and `pid`
      unique = pad(mid, 6, 16) + pad(pid, 4, 16)
  
      // calculate the initial sequence prefix
      seqpref = pad(~~(seq / 16), 5, 16)
  }
docs: Initialize values for calculations.