title: How do you declare an interface in Rust?
body: <p>I have multiple types with similar methods. I want to abstract over them by writing an interface, like I would in Java:</p>
  <pre class="lang-java prettyprint-override"><code>public interface Shape {
      public float area();
  }
  
  class Circle implements Shape {
      public float area() {
          return radius * radius * Math.PI;
      }
  
      public float radius;
  }
  </code></pre>
  <p>However, there is no <code>interface</code> keyword in Rust. Doesn't Rust offer the possibility to abstract over multiple types?</p>