title: falses following trues, getting pairs
body: <p>i have the following table and need all dates or more specific the time difference between row where a true was followed by a false</p>
  <pre><code>         date   sent
  0  2022-06-01   true
  1  2022-06-02   true
  2  2022-06-04  false
  3  2022-06-08   true
  4  2022-06-09   true
  5  2022-06-10  false
  6  2022-06-11  false
  7  2022-06-12  false
  8  2022-06-12   true
  9  2022-06-14   true
  </code></pre>
  <p>i have the following code for falses followed by a true but am stuck to make the vice versa.</p>
  <pre><code># ensure datetime
  df['date'] = pd.to_datetime(df['date'])
  
  # identify False followed by True
  # you can easily adapt to identify the True
  m = df['sent'].shift(-1)&amp;~df['sent']
  
  # slice True, subtract last False
  df.shift(-1).loc[m, 'date'].sub(df.loc[m, 'date'])
  </code></pre>
  <p>it's importnt to only get trues followed by falses(these pairs) and not things in between or falses on falses or trues on trues</p>