public void DefineUnion(IEnumerable<Tuple<String, ExprType>> attribs) {
if (this.IsComplete) {
throw new InvalidOperationException("Redefining a union.");
}
this._attribs = attribs
.Select(attrib => new Utils.StoreEntry(attrib.Item1, attrib.Item2, 0))
.ToList();
this._size_of = this.Attribs.Select(attrib => attrib.type.Alignment).Max();
}