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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def completion_pre_event_input_accelerators(editor, event):
 """ Implements completion pre event input accelerators. :param editor: Document editor. :type editor: QWidget :param event: Event being handled. :type event: QEvent :return: Process event. :rtype: bool """


    process_event = True

    if editor.completer:
        # TODO: Investigate the slowdown on popup visibility test.
        if editor.completer.popup().isVisible():
            if event.key() in (Qt.Key_Enter, Qt.Key_Return, Qt.Key_Escape, Qt.Key_Tab, Qt.Key_Backtab):
                event.ignore()
                process_event = False
                return process_event

    if event.modifiers() in (Qt.ControlModifier, Qt.MetaModifier) and event.key() == Qt.Key_Space:
        process_event = False
        if not editor.completer:
            return process_event

        perform_completion(editor)

    return process_event