Create and return a hashStore implementation based on configuration

def initHashStore(data_dir, name, config=None, read_only=False) -> HashStore:
    """
    Create and return a hashStore implementation based on configuration
    """
    config = config or getConfig()
    hsConfig = config.hashStore['type'].lower()
    if hsConfig == HS_FILE:
        return FileHashStore(dataDir=data_dir,
                             fileNamePrefix=name)
    elif hsConfig == HS_LEVELDB or hsConfig == HS_ROCKSDB:
        return DbHashStore(dataDir=data_dir,
                           fileNamePrefix=name,
                           db_type=hsConfig,
                           read_only=read_only,
                           config=config)
    else:
        return MemoryHashStore()