title: Lua Lanes: attempt to index global 'os' (a nil value)
body: <p>I wanted to use <a href="https://github.com/LuaLanes/lanes" rel="nofollow">Lua Lanes</a> to do a multithreading and record the time taken. Here is the code:</p>
  
  <pre><code>require "lanes"
  
  function performTest ()
      os.execute("testJson-mt.lua")
  end
  
  for i=1,10,1 do
      f= lanes.gen(performTest)
      a=f()
      startTime = os.time()
      print("ID "..a[1].." completed.")
      endTime = os.time()
      diff = os.difftime (endTime, startTime)
      print(i..","..os.date("%x %X",startTime)..","..os.date("%x %X",endTime)..","..startTime..","..endTime..","..diff)
  end
  </code></pre>
  
  <p>However, when I run the code, the console returns an error: <code>lua: testLanes.lua:4: attempt to index global 'os' (a nil value)</code>.</p>
  
  <p>This error code point to this line where <code>os.execute("testJson-mt.lua")</code>. I don't quite understand this error. Please advise.</p>
  
  <p>Note: I am using <a href="https://code.google.com/p/luaforwindows/" rel="nofollow">Lua for Windows</a> as the IDE.</p>