Add helper to sum origin time deltas

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (bf82567) 97.72% compared to head (b585be6) 97.73%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #135 +/- ## ======================================= Coverage 97.72% 97.73% ======================================= Files 620 622 +2 Lines 8524 8556 +32 ======================================= + Hits 8330 8362 +32 Misses 194 194 ``` | [Flag](https://app.codecov.io/gh/mmore500/hstrat/pull/135/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+Andres+Moreno) | Coverage Δ | | |---|---|---| | [tests](https://app.codecov.io/gh/mmore500/hstrat/pull/135/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+Andres+Moreno) | `97.73% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Matthew+Andres+Moreno#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.