code: def append(self, lines):
          
          if isinstance(lines, list):
              self._lines = self._lines + lines
          elif isinstance(lines, str):
              lines = lines.split('\n')
              self._lines = self._lines + lines
          else:
              raise TypeError('Unsupported type {0} for lines.'.format(type(lines)))
docs: Args:
              lines (list): List of line strings to append to the end of the editor