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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 list_roles(self, mount_point=DEFAULT_MOUNT_POINT):
 """List all the roles that are registered with the plugin. Supported methods: LIST: /auth/{mount_point}/roles. Produces: 200 application/json :param mount_point: The "path" the azure auth method was mounted on. :type mount_point: str | unicode :return: The "data" key from the JSON response of the request. :rtype: dict """

        api_path = '/v1/auth/{mount_point}/roles'.format(mount_point=mount_point)
        response = self._adapter.list(
            url=api_path
        )
        return response.json().get('data')