74: closed form calculations for `PWCsurvOS` #298

All 83 tests pass, 1 skipped in 2m 10s

    1 files ±0   16 suites ±0 2m 10s ⏱️ -1s
  84 tests ±0   83 ✔️ ±0 1 💤 ±0 0 ❌ ±0
190 runs ±0 189 ✔️ ±0 1 💤 ±0 0 ❌ ±0

Results for commit 9fd45a9. ± Comparison against earlier commit 6d6d410.