title: How to get datetime from a pandas dataframe by row index
body: <p>How to get the date from this following dataframe by row index? I am looking for a function something like:</p>
  <pre><code>get_datetime(dataframe, row_index = 1)
  </code></pre>
  <p>which will return the datetime as <code>2022-01-11</code></p>
  <p>I have read the <a href="https://pandas.pydata.org/docs/user_guide/timeseries.html" rel="nofollow noreferrer">Time series / date functionality of Pandas</a>, however, did not see anything useful there.</p>
  <pre><code>             open   high    low  close    volume  dividends  stock splits
  Date                                                                     
  2022-01-06  21.99  22.22  21.59  22.18   1956300          0             0
  2022-01-11  22.32  22.93  22.23  22.92   1885700          0             0
  2022-01-21  22.40  22.55  22.02  22.13   2265500          0             0
  2022-01-26  22.28  22.72  21.79  22.05   2247600          0             0
  2022-01-31  22.02  22.92  21.72  22.86   2955500          0             0
  2022-02-10  24.73  25.51  24.59  25.29   4069300          0             0
  2022-02-15  24.85  25.57  24.56  25.47   5661100          0             0
  2022-02-25  24.59  25.07  24.46  24.67   3722400          0             0
  2022-03-02  23.20  23.95  23.15  23.82   3268100          0             0
  2022-03-07  21.54  21.60  19.51  19.59  10102600          0             0
  </code></pre>