'Set up connection with a SQLite :attr:`database`.
.. note:: This is a `classmethod`.
:param database: Path to a SQLite database file.
`./hostslist.s3db` by default.
:type database: str'

@classmethod
def connect_db(cls, database=DATABASE):

    cls.conn = sqlite3.connect(database)
    cls._cur = cls.conn.cursor()
    cls._database = database
