finish dv-part 1
Revert "finish dv-part 1"

This reverts commit 2c8610f28b68afdb2615fa4c5cc344c7889c9d43.
Revert "Revert "finish dv-part 1""

This reverts commit 7e3aaf937859521a9ab84ec38ff50a7a107d07dd.