code: func (fb *Firebase) Push(v interface{}) (*Firebase, error) {
  	bytes, err := json.Marshal(v)
  	if err != nil {
  		return nil, err
  	}
  	_, bytes, err = fb.doRequest("POST", bytes)
  	if err != nil {
  		return nil, err
  	}
  	var m map[string]string
  	if err := json.Unmarshal(bytes, &m); err != nil {
  		return nil, err
  	}
  	newRef := fb.copy()
  	newRef.url = fb.url + "/" + m["name"]
  	return newRef, err
  }
docs: // Push creates a reference to an auto-generated child location.