Revert "fixup! Bugfix: fixed interpretation of timesteps in assertion and code; timesteps should be 1-based, not 0-based"

This reverts commit f9aef941b3f7347879c844376fc86f73f9046587.
Revert "fixup! Bugfix: fixed interpretation of timesteps in assertion and code; timesteps should be 1-based, not 0-based"

This reverts commit fc3faa1da88657a978f0eb2b9483007267d1aab6.
Revert "Bugfix: fixed interpretation of timesteps in assertion and code; timesteps should be 1-based, not 0-based"

This reverts commit 9f3e6ea08d622b8c9fc47f4a6ece67843347c1e7.