'Unzip the archived :attr:`datafile` to a SQLite database file
:attr:`database`.
.. note:: This is a `classmethod`.
:param datafile: Path to the zipped data file. `./hostslist.data` by
default.
:type datafile: str
:param database: Path to a SQLite database file. `./hostslist.s3db` by
default.
:type database: str'

@classmethod
def unpack(cls, datafile=DATAFILE, database=DATABASE):

    datafile = zipfile.ZipFile(datafile, 'r')
    (path, filename) = os.path.split(database)
    datafile.extract(filename, path)
