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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 widget(self, f):
 """ Return an interactive function widget for the given function. The widget is only constructed, not displayed nor attached to the function. Returns ------- An instance of ``self.cls`` (typically :class:`interactive`). Parameters f : function The function to which the interactive widgets are tied. """

        return self.cls(f, self.opts, **self.kwargs)