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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 asset(self, asset_id, query=None):
 """Fetches an Asset by ID. API Reference: https://www.contentful.com/developers/docs/references/content-delivery-api/#/reference/assets/asset/get-a-single-asset :param asset_id: The ID of the target Asset. :param query: (optional) Dict with API options. :return: :class:`Asset <Asset>` object. :rtype: contentful.asset.Asset Usage: """


        return self._get(
            self.environment_url(
                '/assets/{0}'.format(asset_id)
            ),
            query
        )