CreateDB constructs a `DB`.

NewFileLock returns a new file based lock manager.

NewProvider constructs a Provider.

NewUpdateBatch constructs an instance of a Batch.

Conf configuration for `Provider` `ExpectedFormatVersion` is the expected value of the format key in the internal database.

DB - a wrapper on an actual store.

DBHandle is an handle to a named db.

FileLock encapsulate the DB that holds the file lock.

Iterator extends actual leveldb iterator.

Provider enables to use a single leveldb as multiple logical leveldbs.

UpdateBatch encloses the details of multiple `updates`.