code: def add_from_existing(self, resource, timeout=-1):
          
          uri = self.URI + "/from-existing"
          return self._client.create(resource, uri=uri, timeout=timeout)
docs: Adds a volume that already exists in the Storage system
  
          Args:
              resource (dict):
                  Object to create.
              timeout:
                  Timeout in seconds. Wait for task completion by default. The timeout does not abort the operation
                  in OneView, just stop waiting for its completion.
  
          Returns:
              dict: Added resource.