title: Copying all elements of a map into another
body: <p>Given</p>
  
  <pre><code>var dst, src map[K]V
  </code></pre>
  
  <p>I can copy all entries from <code>src</code> into <code>dst</code> by doing</p>
  
  <pre><code>for k, v := range src {
      dst[k] = v
  }
  </code></pre>
  
  <p>Is there a more idiomatic way to do this?</p>
  
  <p><code>copy</code> only works on slices (and <code>string</code> as a source).</p>