'Constructor for ABNF.
please check RFC for arguments.'

def __init__(self, fin=0, rsv1=0, rsv2=0, rsv3=0, opcode=OPCODE_TEXT, mask=1, data=''):

    self.fin = fin
    self.rsv1 = rsv1
    self.rsv2 = rsv2
    self.rsv3 = rsv3
    self.opcode = opcode
    self.mask = mask
    if (data is None):
        data = ''
    self.data = data
    self.get_mask_key = os.urandom
