Should I leave off the example import (ie will the compilation of the release notes actually run teh code)?

For example, is this enough:
```
   .. ipython:: python
   
      df = DataFrame([ Timestamp('20010101'),
                       Timestamp('20040601') ], columns=['age'])
      df['today'] = Timestamp('20130419')
      df['diff'] = df['today']-df['age']
      df
```