docs: def cell_to_text(self):
          """Return the text representation of a cell"""
          if self.cell_type == 'markdown':
              # Is an explicit region required?
              if self.metadata or self.cell_reader(self.fmt).read(self.source)[1] < len(self.source):
                  if self.metadata:
                      region_start = ['<!-- #region']
                      if 'title' in self.metadata and '{' not in self.metadata['title']:
                          region_start.append(self.metadata.pop('title'))
                      region_start.append(json.dumps(self.metadata))
                      region_start.append('-->')
                      region_start = ' '.join(region_start)
                  else:
                      region_start = '<!-- #region -->'
  
                  return [region_start] + self.source + ['<!-- #endregion -->']
              return self.source
  
          return self.code_to_text()