Extend current selection to complete lines

def extend_selection_to_complete_lines(self):
        """Extend current selection to complete lines"""
        cursor = self.textCursor()
        start_pos, end_pos = cursor.selectionStart(), cursor.selectionEnd()
        cursor.setPosition(start_pos)
        cursor.setPosition(end_pos, QTextCursor.KeepAnchor)
        if cursor.atBlockStart():
            cursor.movePosition(QTextCursor.PreviousBlock,
                                QTextCursor.KeepAnchor)
            cursor.movePosition(QTextCursor.EndOfBlock,
                                QTextCursor.KeepAnchor)
        self.setTextCursor(cursor)