title: Meaning of a struct with embedded anonymous interface?
body: <p><a href="https://golang.org/src/sort/sort.go" rel="noreferrer"><code>sort</code></a> package:</p>
  <pre><code>type Interface interface {
      Len() int
      Less(i, j int) bool
      Swap(i, j int)
  }
  
  ...
  
  type reverse struct {
      Interface
  }
  </code></pre>
  <p>What is the meaning of anonymous interface <code>Interface</code> in struct <code>reverse</code>?</p>