Redefines :meth:`~candv.base.Constant.merge_into_group` and adds
        ``value`` attribute to the target group.

def merge_into_group(self, group):
        """
        Redefines :meth:`~candv.base.Constant.merge_into_group` and adds
        ``value`` attribute to the target group.
        """
        super(ValueConstant, self).merge_into_group(group)
        group.value = self.value