title: How to check if interface{} is a slice
body: <p>I'm noob in Go :) so my question may be stupid, but can't find answer, so.</p>
  
  <p>I need a function:</p>
  
  <pre><code>func name (v interface{}) {
      if is_slice() {
          for _, i := range v {
              my_var := i.(MyInterface)
              ... do smth
          }
      } else {
          my_var := v.(MyInterface)
          ... do smth
      }
  }
  </code></pre>
  
  <p>How can I do <code>is_slice</code> in Go? Appreciate any help.</p>