def __init__(self, number, serialBits=32):
        """
        Construct an L{SerialNumber} instance.

        @param number: An L{int} which will be stored as the modulo
            C{number % 2 ^ serialBits}
        @type number: L{int}

        @param serialBits: The size of the serial number space. The power of two
            which results in one larger than the largest integer corresponding
            to a serial number value.
        @type serialBits: L{int}
        """
        self._serialBits = serialBits
        self._modulo = 2 ** serialBits
        self._halfRing = 2 ** (serialBits - 1)
        self._maxAdd = 2 ** (serialBits - 1) - 1
        self._number = int(number) % self._modulo

        Construct an L{SerialNumber} instance.

        @param number: An L{int} which will be stored as the modulo
            C{number % 2 ^ serialBits}
        @type number: L{int}

        @param serialBits: The size of the serial number space. The power of two
            which results in one larger than the largest integer corresponding
            to a serial number value.
        @type serialBits: L{int}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/_rfc1982.py