title: AttributeError: module 'databricks.koalas' has no attribute 'DateOffset'
body: <p>I am working on replacing Pandas library to Koalas Library in my python repo in VS Code. But Koalas module does not seem to have DateOffset() module similar to what pandas has.</p>
  <p>I tried this :</p>
  <pre><code>import databricks.koalas as ks 
  kdf[&quot;date_col_2&quot;] = kdf[&quot;date_col_1&quot;] - ks.DateOffset(months=cycle_info_gap)
  </code></pre>
  <p>It results in the below error :</p>
  <pre><code>AttributeError: module 'databricks.koalas' has no attribute 'DateOffset'
  </code></pre>
  <p>Is there any alternative for this in Koalas?</p>