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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 renderer(name):
 """ Helper utility to access the active renderer for a given extension. """

    try:
        if name not in Store.renderers:
            extension(name)
        return Store.renderers[name]
    except ImportError:
        msg = ('Could not find a {name!r} renderer, available renderers are: {available}.')
        available = ', '.join(repr(k) for k in Store.renderers)
        raise ImportError(msg.format(name=name, available=available))