Method invocations based on HasField
5
so far - 5
color  - "red"
so far - so far - 7
color  - "red"
mass  - 14.7
42
Nominal subtyping with explicit up-cast
5
so far - 5
color  - "red"
42
so far - so far - 7
color  - "red"
mass  - 14.7
Nominal subtyping with implicit up-cast
5
so far - 5
color  - "red"
42
so far - so far - 7
color  - "red"
mass  - 14.7
so far - so far - 7
color  - "red"
mass  - 14.7
    after moving MP...
so far - so far - 17
color  - "red"
mass  - 14.7
42