code: func (s *SkipList) Seek(key interface{}) Iterator {
  	current := s.getPath(s.header, nil, key)
  	if current == nil {
  		return nil
  	}
  
  	return &iter{
  		current: current,
  		key:     current.key,
  		list:    s,
  		value:   current.value,
  	}
  }
docs: // Seek returns a bidirectional iterator starting with the first element whose
  // key is greater or equal to key; otherwise, a nil iterator is returned.