code: func (tree *btree) Get(keys ...Key) Keys {
  	results := make(Keys, 0, len(keys))
  	for _, k := range keys {
  		results = append(results, tree.get(k))
  	}
  
  	return results
  }
docs: // Get will retrieve any keys matching the provided keys in the tree.
  // Returns nil in any place of a key that couldn't be found.  Each lookup
  // is an O(log n) operation.