Append an entry to history filename.

        Args:
            filename (str): file to be updated in a new tab.
            command (str): line to be added.
            go_to_eof (bool): scroll to the end of file.

def append_to_history(self, filename, command, go_to_eof):
        """
        Append an entry to history filename.

        Args:
            filename (str): file to be updated in a new tab.
            command (str): line to be added.
            go_to_eof (bool): scroll to the end of file.
        """
        if not is_text_string(filename): # filename is a QString
            filename = to_text_string(filename.toUtf8(), 'utf-8')
        command = to_text_string(command)
        index = self.filenames.index(filename)
        self.editors[index].append(command)
        if go_to_eof:
            self.editors[index].set_cursor_position('eof')
        self.tabwidget.setCurrentIndex(index)