code: func (list *LinkedList) RemoveFront() (interface{}, bool) {
  	list.key.Lock()
  	defer list.key.Unlock()
  
  	if list.first == nil {
  		return nil, false
  	}
  
  	retval := list.first.payload
  
  	list.first = list.first.next
  	list.length--
  
  	if 0 == list.length {
  		list.last = nil
  	}
  
  	return retval, true
  }
docs: // RemoveFront returns the entry logically stored at the front of this list and removes it.