title: How to have multiple files with one module?
body: <p>I don't understand why we have only one file per module.</p>
  
  <pre><code>// main.rs
  
  mod dog; // Find dog in dog.rs or dog/mod.rs
  fn main() {
      dog::sonic_bark();
  }
  </code></pre>
  
  <p>When <code>dog</code> grows larger and has lots of functions, it's not good to have all of them in one file.</p>
  
  <p>How I can separate them without using</p>
  
  <pre><code>dog::leg::walk();
  dog::head::nose::smell();
  dog::tail::iron_tail();
  dog::mouth::sonic_bark();
  </code></pre>
  
  <p>I want to just use <code>dog::sonic_bark();</code></p>