def __init__(self, userdb=None, parseKey=keys.Key.fromString):
        """
        Initializes a new L{UNIXAuthorizedKeysFiles}.

        @param userdb: access to the Unix user account and password database
            (default is the Python module L{pwd})
        @type userdb: L{pwd}-like object

        @param parseKey: a callable that takes a string and returns a
            L{twisted.conch.ssh.keys.Key}, mainly to be used for testing.  The
            default is L{twisted.conch.ssh.keys.Key.fromString}.
        @type parseKey: L{callable}
        """
        self._userdb = userdb
        self._parseKey = parseKey
        if userdb is None:
            self._userdb = pwd

        Initializes a new L{UNIXAuthorizedKeysFiles}.

        @param userdb: access to the Unix user account and password database
            (default is the Python module L{pwd})
        @type userdb: L{pwd}-like object

        @param parseKey: a callable that takes a string and returns a
            L{twisted.conch.ssh.keys.Key}, mainly to be used for testing.  The
            default is L{twisted.conch.ssh.keys.Key.fromString}.
        @type parseKey: L{callable}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/checkers.py