title: Why does Flow require annotation of parameter of exported function?
body: <p>Following code (<a href="https://flowtype.org/try/#0PQKgBAAgZgNg9gdzCYAoVUCuA7AxgFwEs5swBDACgAcBKMAbwF9UBbOAE0xgFMA6bgB5U4AJ3wBnMAF5yQA" rel="nofollow noreferrer">Flow playground</a>):</p>
  
  <pre class="lang-flow prettyprint-override"><code>/* @flow */
  
  function a(p) {}
  module.exports = a
  </code></pre>
  
  <p>throws exception</p>
  
  <pre><code>3: function a(p) {}
                ^ parameter `p`. Missing annotation
  </code></pre>
  
  <p>Why is that? I'd expect that type <code>any</code> would be automatically assumed for the parameter <code>p</code>.</p>