CreateExtension.
        [Preview API]
        :param object upload_stream: Stream to upload
        :rtype: :class:`<PublishedExtension> <azure.devops.v5_1.gallery.models.PublishedExtension>`

def create_extension(self, upload_stream, **kwargs):
        """CreateExtension.
        [Preview API]
        :param object upload_stream: Stream to upload
        :rtype: :class:`<PublishedExtension> <azure.devops.v5_1.gallery.models.PublishedExtension>`
        """
        if "callback" in kwargs:
            callback = kwargs["callback"]
        else:
            callback = None
        content = self._client.stream_upload(upload_stream, callback=callback)
        response = self._send(http_method='POST',
                              location_id='a41192c8-9525-4b58-bc86-179fa549d80d',
                              version='5.1-preview.2',
                              content=content,
                              media_type='application/octet-stream')
        return self._deserialize('PublishedExtension', response)