code: func (iter *dbCacheIterator) Seek(key []byte) bool {
  	// Seek to the provided key in both the database and cache iterators
  	// then choose the iterator that is both valid and has the larger key.
  	iter.dbIter.Seek(key)
  	iter.cacheIter.Seek(key)
  	return iter.chooseIterator(true)
  }
docs: // Seek positions the iterator at the first key/value pair that is greater than
  // or equal to the passed seek key.  Returns false if no suitable key was found.
  //
  // This is part of the leveldb iterator.Iterator interface implementation.