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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 get_all_widget_classes():
 """returns collected Leonardo Widgets if not declared in settings is used __subclasses__ which not supports widget subclassing """

    from leonardo.module.web.models import Widget
    _widgets = getattr(settings,
                       'WIDGETS', Widget.__subclasses__())
    widgets = []
    if isinstance(_widgets, dict):
        for group, widget_cls in six.iteritems(_widgets):
            widgets.extend(widget_cls)
    elif isinstance(_widgets, list):
        widgets = _widgets
    return load_widget_classes(widgets)