code: func (h *Server) GetFormation(w http.ResponseWriter, r *http.Request) error {
  	ctx := r.Context()
  
  	app, err := h.findApp(r)
  	if err != nil {
  		return err
  	}
  
  	formation, err := h.ListScale(ctx, app)
  	if err != nil {
  		return err
  	}
  
  	var resp []*Formation
  	for name, proc := range formation {
  		resp = append(resp, &Formation{
  			Type:     name,
  			Quantity: proc.Quantity,
  			Size:     proc.Constraints().String(),
  		})
  	}
  
  	w.WriteHeader(200)
  	return Encode(w, resp)
  }
docs: // ServeHTTPContext handles the http response