Get the bundle visualization.

        @param bundle_id The ID of the bundle.
        @param channel Optional channel name.

def bundle_visualization(self, bundle_id, channel=None):
        '''Get the bundle visualization.

        @param bundle_id The ID of the bundle.
        @param channel Optional channel name.
        '''
        url = self.bundle_visualization_url(bundle_id, channel=channel)
        response = self._get(url)
        return response.content