The type or namespace name 'Helper' does not exist in the namespace 'Google.Apis.Samples
<p>I have added namespace <code>using Google.Apis.Samples.Helper;</code> but after running code I am getting below error which dll I have to add?</p>

<blockquote>
  <blockquote>
    <p>The type or namespace name 'Helper' does not exist in the namespace 'Google.Apis.Samples</p>
  </blockquote>
</blockquote>
