code: def to_text(self):
          
          row = '---\n'
          for index, cell in enumerate(self.cells):
              if index > 0:
                  row += ', '
              row += cell.to_text()
          row += '---'
  
          return row
docs: Render a Text MessageElement as plain text
  
          :returns: The plain text representation of the row.
          :rtype: basestring