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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 pretty_print_config_to_json(self, services, hostname=None):
 """JSON string description of a protorpc.remote.Service in API format. Args: services: Either a single protorpc.remote.Service or a list of them that implements an api/version. hostname: string, Hostname of the API, to override the value set on the current service. Defaults to None. Returns: string, The API descriptor document as a JSON string. """

    descriptor = self.get_config_dict(services, hostname)
    return json.dumps(descriptor, sort_keys=True, indent=2,
                      separators=(',', ': '))