def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def message_data(self):
        if self.proto_view == 0:
            return self.message.plain_bits_str
        elif self.proto_view == 1:
            return self.message.plain_hex_str
        elif self.proto_view == 2:
            return self.message.plain_ascii_str
        else:
            return None