code: func (m *Mux) ExecuteString(name string, binding interface{}, options ...map[string]interface{}) (result string, err error) {
  	out := m.buffer.Get()
  	defer m.buffer.Put(out)
  	err = m.ExecuteWriter(out, name, binding, options...)
  	if err == nil {
  		result = out.String()
  	}
  	return
  }
docs: // ExecuteString executes a template from a specific template engine and returns its contents result as string, it doesn't renders