code: func (e *ClientExecutor) Build(b *imagebuilder.Builder, node *parser.Node, from string) error {
  	defer e.Release()
  	if err := e.Prepare(b, node, from); err != nil {
  		return err
  	}
  	if err := e.Execute(b, node); err != nil {
  		return err
  	}
  	return e.Commit(b)
  }
docs: // Build is a helper method to perform a Docker build against the
  // provided Docker client. It will load the image if not specified,
  // create a container if one does not already exist, and start a
  // container if the Dockerfile contains RUN commands. It will cleanup
  // any containers it creates directly, and set the e.Image.ID field
  // to the generated image.