code: func (snap *dbCacheSnapshot) Has(key []byte) bool {
  	// Check the cached entries first.
  	if snap.pendingRemove.Has(key) {
  		return false
  	}
  	if snap.pendingKeys.Has(key) {
  		return true
  	}
  
  	// Consult the database.
  	hasKey, _ := snap.dbSnapshot.Has(key, nil)
  	return hasKey
  }
docs: // Has returns whether or not the passed key exists.