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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 response_as_single(self, copy=0):
 """ convert the response map to a single data frame with Multi-Index columns """

        arr = []
        for sid, frame in self.response.iteritems():
            if copy:
                frame = frame.copy()
            'security' not in frame and frame.insert(0, 'security', sid)
            arr.append(frame.reset_index().set_index(['date', 'security']))
        return concat(arr).unstack()