title: What's the meaning of "void = () => {}" after Fat arrow function in TypeScript?
body: <p>I saw this block of code in our code base and I have a bit of a problem to understand <code>void = (page)</code>. According to <a href="https://stackoverflow.com/a/34274584/513413">https://stackoverflow.com/a/34274584/513413</a>, the return type is coming after <code>=&gt;</code> which is <code>void</code> in my case. So what does <code>= (page) =&gt; {}</code> do? 
  What is its equivalent function if I don't write it with fat arrow function?</p>
  
  <p>This is the code:</p>
  
  <pre><code>private navigateTo: (page: string) =&gt; void = (page) =&gt; {
      // display page
  }
  </code></pre>