Records the vertices and edges of a control flow graph instead of building it, as the bottom-up fold would
copy an eager graph once per nesting level. mergeWith() only references the other
builder, materialize() replays everything once in recording order — the
order an eager merge produced, which the vertex order of a function definition's children relies on.
Records the vertices and edges of a control flow graph instead of building it, as the bottom-up fold would copy an eager graph once per nesting level. mergeWith() only references the other builder, materialize() replays everything once in recording order — the order an eager merge produced, which the vertex order of a function definition's children relies on.