Indents text at cursor position.

def indent(self):
        """
        Indents text at cursor position.
        """
        cursor = self.editor.textCursor()
        assert isinstance(cursor, QtGui.QTextCursor)
        if cursor.hasSelection():
            self.indent_selection(cursor)
        else:
            # simply insert indentation at the cursor position
            tab_len = self.editor.tab_length
            if cursor.positionInBlock() < self.min_column and not cursor.atBlockEnd():
                cursor.movePosition(cursor.Right, cursor.MoveAnchor, self.min_column)
            cursor.beginEditBlock()
            if self.editor.use_spaces_instead_of_tabs:
                nb_space_to_add = tab_len - (cursor.positionInBlock() - self.min_column) % tab_len
                cursor.insertText(nb_space_to_add * " ")
            else:
                cursor.insertText('\t')
            cursor.endEditBlock()
            self.editor.setTextCursor(cursor)