title: Replace change of line with condition in multiple lines
body: <p>I have a text file, like this:</p>
  <pre><code>3/11/21, 6:13 PM - Gil: X1000
  3/11/21, 6:15 PM - Sergio: &lt;Media omitted&gt;
  3/11/21, 6:19 PM - Sergio: X400
  3/11/21, 6:20 PM - Sergio: Los amigos de vonzo en Francia:
  
  1. La Tóxica
  2. El brujo vodoo
  3. El/La Zoofilic@
  3/11/21, 6:20 PM - Sergio: :V
  3/11/21, 6:21 PM - Joan :V: JAJAJAJAJA
  </code></pre>
  <p>Most of the lines start with a date/time that is easy to catch with a regular expression.</p>
  <p>I would like to delete the change of line when the date/time is not found, I would expect something like (<strong>in a new file</strong>):</p>
  <pre><code>3/11/21, 6:13 PM - Gil: X1000
  3/11/21, 6:15 PM - Sergio: &lt;Media omitted&gt;
  3/11/21, 6:19 PM - Sergio: X400
  3/11/21, 6:20 PM - Sergio: Los amigos de vonzo en Francia: 1. La Tóxica 2. El brujo vodoo 3. El/La Zoofilic@
  3/11/21, 6:20 PM - Sergio: :V
  3/11/21, 6:21 PM - Joan :V: JAJAJAJAJA
  </code></pre>
  <p>The problem I have is that I'm reading the file as:</p>
  <pre><code>        input_file = open(self.fileName, encoding=&quot;utf8&quot; , errors='replace')
          for line in input_file:
              output.write(re.sub(#SOMETHING))
  </code></pre>
  <p>With this is that I can only read only line at the time and I don't really get how to change the <code>n</code> line with a condition in line <code>n+1</code>.</p>
  <p>How can I change line change the <code>n</code> line with a condition in line <code>n+1</code>?</p>