code: func (r *ResponseDefinition) Dup() *ResponseDefinition {
  	res := ResponseDefinition{
  		Name:        r.Name,
  		Status:      r.Status,
  		Description: r.Description,
  		MediaType:   r.MediaType,
  		ViewName:    r.ViewName,
  	}
  	if r.Headers != nil {
  		res.Headers = DupAtt(r.Headers)
  	}
  	return &res
  }
docs: // Dup returns a copy of the response definition.