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+//: Exclusive containers contain exactly one of a fixed number of 'variants'
+//: of different types.
+//:
+//: They also implicitly contain a tag describing precisely which variant is
+//: currently stored in them.
+
+:(before "End Mu Types Initialization")
+//: We'll use this container as a running example, with two integer elements.
+{
+int tmp = Type_number["integer-or-point"] = Next_type_number++;
+Type[tmp].size = 2;
+Type[tmp].kind = exclusive_container;
+Type[tmp].name = "integer-or-point";
+//? cout << tmp << ": " << Type[tmp].elements.size() << '\n'; //? 1
+vector<type_number> t1;
+t1.push_back(integer);
+Type[tmp].elements.push_back(t1);
+//? cout << Type[tmp].elements.size() << '\n'; //? 1
+vector<type_number> t2;
+t2.push_back(point);
+Type[tmp].elements.push_back(t2);
+//? cout << Type[tmp].elements.size() << '\n'; //? 1
+//? cout << "point: " << point << '\n'; //? 1
+Type[tmp].element_names.push_back("i");
+Type[tmp].element_names.push_back("p");
+}
+
+:(scenario "copy_exclusive_container")
+# Copying exclusive containers copies all their contents and an extra location for the tag.
+recipe main [
+  1:integer <- copy 1:literal  # 'point' variant
+  2:integer <- copy 34:literal
+  3:integer <- copy 35:literal
+  4:integer-or-point <- copy 1:integer-or-point
+]
++mem: storing 1 in location 4
++mem: storing 34 in location 5
++mem: storing 35 in location 6
+
+:(before "End size_of(types) Cases")
+if (t.kind == exclusive_container) {
+  // size of an exclusive container is the size of its largest variant
+//?   cout << "--- " << types[0] << ' ' << t.size << '\n'; //? 1
+//?   cout << "point: " << Type_number["point"] << " " << Type[Type_number["point"]].name << " " << Type[Type_number["point"]].size << '\n'; //? 1
+//?   cout << t.name << ' ' << t.size << ' ' << t.elements.size() << '\n'; //? 1
+  size_t result = 0;
+  for (size_t i = 0; i < t.size; ++i) {
+    size_t tmp = size_of(t.elements[i]);
+//?     cout << i << ": " << t.elements[i][0] << ' ' << tmp << ' ' << result << '\n'; //? 1
+    if (tmp > result) result = tmp;
+  }
+  // ...+1 for its tag.
+  return result+1;
+}