title: Why does "not nil" return true in Lua?
body: <p>I have used repl.it to see what it returned, just for the sake of curiosity, and it turned out that 
  <code>not nil</code>
  returnes <code>true</code></p>
  
  <p>Why is it? Is it because in Lua everything should be rather true or false in the end?</p>
  
  <p>Repl.it link: <a href="https://repl.it/repls/SanePastelHarrier" rel="nofollow noreferrer">https://repl.it/repls/SanePastelHarrier</a></p>