title: Deleting rows which sum to zero in 1 column (like pairs) but some elements in other columns are different
body: <p>Consider a dataframe like</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>product</th>
  <th>date</th>
  <th>value</th>
  <th>city</th>
  <th>reference</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>y</td>
  <td>21-01-2020</td>
  <td>-16</td>
  <td>Paris</td>
  <td>xji</td>
  </tr>
  <tr>
  <td>x</td>
  <td>25-01-2020</td>
  <td>-16</td>
  <td>Munich</td>
  <td>zyc</td>
  </tr>
  <tr>
  <td>x</td>
  <td>01-05-2020</td>
  <td>16</td>
  <td>Munich</td>
  <td>dkj</td>
  </tr>
  <tr>
  <td>y</td>
  <td>20-01-2020</td>
  <td>-20</td>
  <td>Paris</td>
  <td>jkdl</td>
  </tr>
  <tr>
  <td>z</td>
  <td>21-01-2020</td>
  <td>30</td>
  <td>Munich</td>
  <td>212jio</td>
  </tr>
  <tr>
  <td>t</td>
  <td>05-01-2020</td>
  <td>2</td>
  <td>Munich</td>
  <td>jidi1</td>
  </tr>
  <tr>
  <td>y</td>
  <td>21-03-2020</td>
  <td>20</td>
  <td>Paris</td>
  <td>reg1</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>I would like to delete rows that value cancel each other, having something like</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>product</th>
  <th>date</th>
  <th>value</th>
  <th>city</th>
  <th>reference</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>y</td>
  <td>21-01-2020</td>
  <td>-16</td>
  <td>Paris</td>
  <td>xji</td>
  </tr>
  <tr>
  <td>z</td>
  <td>21-01-2020</td>
  <td>30</td>
  <td>Munich</td>
  <td>212jio</td>
  </tr>
  <tr>
  <td>t</td>
  <td>05-01-2020</td>
  <td>2</td>
  <td>Munich</td>
  <td>jidi1</td>
  </tr>
  </tbody>
  </table>
  </div>