Write docstring to editor by shortcut of code editor.

def write_docstring_for_shortcut(self):
        """Write docstring to editor by shortcut of code editor."""
        # cursor placed below function definition
        result = self.get_function_definition_from_below_last_line()
        if result is not None:
            __, number_of_lines_of_function = result
            cursor = self.code_editor.textCursor()
            for __ in range(number_of_lines_of_function):
                cursor.movePosition(QTextCursor.PreviousBlock)

            self.code_editor.setTextCursor(cursor)

        cursor = self.code_editor.textCursor()
        self.line_number_cursor = cursor.blockNumber() + 1

        self.write_docstring_at_first_line_of_function()