Create an instance
        
        Args:
            instance (AtlasServiceInstance.Instance): Existing or New instance
            parameters (dict): Parameters for the instance
            
        Keyword Arguments:
            existing (bool): True (use an existing cluster), False (create a new cluster)
        
        Returns:
            ProvisionedServiceSpec: Status

def create(self, instance, parameters, existing=True):
        """Create an instance
        
        Args:
            instance (AtlasServiceInstance.Instance): Existing or New instance
            parameters (dict): Parameters for the instance
            
        Keyword Arguments:
            existing (bool): True (use an existing cluster), False (create a new cluster)
        
        Returns:
            ProvisionedServiceSpec: Status
        """
        return self.service_instance.create(instance, parameters, existing)