title: What are the paths that "require" looks up by default?
body: <p>In Ruby, I have been told that when doing</p>
  
  <pre><code>require "some_file"
  </code></pre>
  
  <p>Ruby will look for the file in certain places.</p>
  
  <p>I know that it looks for <code>some_file.rb</code>, but where does it look for it by default?</p>