title: Is there something in Python that is similar to Harmony's let keyword?
body: <p>In Harmony, there is a <code>let</code> keyword that allows for declaration of variables that are scoped to the nearest block. For example</p>
  
  <pre><code>function foo() {
      if (true){
          let a = 100;
      }
      return a
  }
  </code></pre>
  
  <p>will result in an error since <code>a</code> is only defined inside the <code>if</code> block.</p>
  
  <p>I know I can use <code>del</code> to achieve the same thing, but that that is manual instead of automatic like the <code>let</code> keyword</p>