Get the text to put in the header of the levels of the indexes.

        By default it returns 'Index i', where i is the section in the index

def headerData(self, section, orientation, role):
        """
        Get the text to put in the header of the levels of the indexes.

        By default it returns 'Index i', where i is the section in the index
        """
        if role == Qt.TextAlignmentRole:
            if orientation == Qt.Horizontal:
                return Qt.AlignCenter | Qt.AlignBottom
            else:
                return Qt.AlignRight | Qt.AlignVCenter
        if role != Qt.DisplayRole and role != Qt.ToolTipRole:
            return None
        if self.model.header_shape[0] <= 1 and orientation == Qt.Horizontal:
            if self.model.name(1,section):
                return self.model.name(1,section)
            return _('Index')
        elif self.model.header_shape[0] <= 1:
            return None
        elif self.model.header_shape[1] <= 1 and orientation == Qt.Vertical:
            return None
        return _('Index') + ' ' + to_text_string(section)