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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 plotly_class(name=None, slug=None, da=None, prefix=None, postfix=None, template_type=None):
    'Return a string of space-separated class names'

    da, app = _locate_daapp(name, slug, da)

    return app.extra_html_properties(prefix=prefix,
                                     postfix=postfix,
                                     template_type=template_type)