title: Calculate end date in Python given the start date and a varying duration
body: <p>I am trying to calculate the end dates of contracts.  I know the start dates and the durations.  The durations vary by contract.
  Here is what the dataframe looks like</p>
  
  <pre><code>contract_start  Contract Duration
  15459   2019-09-01  6
  19987   2020-01-01  12
  11445   2019-02-01  1
  7278    2019-10-01  12
  12783   2020-03-01  7
  </code></pre>
  
  <p>I have tried this code</p>
  
  <pre><code>testdf['contract_end'] = testdf['contract_start']+ pd.tseries.offsets.DateOffset(months=testdf['Contract Duration'])
  </code></pre>
  
  <p>It gives me this error:  TypeError: cannot convert the series to class 'int'</p>
  
  <p>I'm guessing I need a way to iterate through the contract duration, but have not been able to figure it out.  Appreciate any help.  Thanks.</p>