Bistro_engine.DbSourceA database to cache workflow result and execution traces
It is implemented as a directory in the file system.
An abstract type for databases
init path creates a database located at path path, which can be absolute or relative. If the path already exists, its contents is inspected to see if it looks like a bistro database; if not, a fresh database is created on the filesystem.
Returns an error message if path is occupied with something else than a bistro database.