code: def create_header(self, depth):
          
          if not (depth >= 0 and depth < len(self._headertexts)):
              return
          txt = self._headertexts[depth]
          if txt is None:
              return
          lbl = QtGui.QLabel(txt, self)
          return lbl
docs: Create and return a widget that will be used as a header for the given depth
  
          Override this method if you want to have header widgets.
          The default implementation returns None.
          You can return None if you do not want a header for the given depth
  
          :param depth: the depth level
          :type depth: int
          :returns: a Widget that is used for the header or None
          :rtype: QtGui.QWidget|None
          :raises: None