Revert "Implementation interface tweak (Sorry, Kasper!)"

This reverts commit afc159fe1a941fa634acbf1b84df84d15a2243f7.
Revert "Revert "Implementation interface tweak (Sorry, Kasper!)""

This reverts commit cce1e2473f75a50acc28475f082c2f52ab0a9248.
Revert "Revert "Revert "Implementation interface tweak (Sorry, Kasper!)"""

This reverts commit fd9d9df732a7cb9b2aea7a5b6f4e8b41529cb609.