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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 add_version(self, project, version, egg):
 """ Adds a new project egg to the Scrapyd service. First class, maps to Scrapyd's add version endpoint. """

        url = self._build_url(constants.ADD_VERSION_ENDPOINT)
        data = {
            'project': project,
            'version': version
        }
        files = {
            'egg': egg
        }
        json = self.client.post(url, data=data, files=files,
                                timeout=self.timeout)
        return json['spiders']