This backend allows creating a `Wallet` instance without network connection or even without the
wallet itself. In version 0.5 the only practical use is to cold-generate
:doc:`subaddresses <address>` like in the example below:
..code-block:: python
In [8]: w = Wallet(OfflineWallet('47ewoP19TN7JEEnFKUJHAYhGxkeTRH82sf36giEp9AcNfDBfkAtRLX7A6rZz18bbNHPNV7ex6WYbMN3aKisFRJZ8Ebsmgef', view_key='6d9056aa2c096bfcd2f272759555e5764ba204dd362604a983fa3e0aafd35901'))