ASSIGN_LEFT:
Substitutor: <empty substitutor>
Substituted pairs:
Child <: Base (Original: Child <: Base)

ASSIGN_RIGHT:
Substitutor: <empty substitutor>
Substituted pairs:
Child <: Base (Original: Child <: Base)

ASSIGN_ALL:
Substitutor: <empty substitutor>
Substituted pairs:
Child <: Base (Original: Child <: Base)
