This version coincides with the release of Hemingway and Henkes (2021) _Earth Planet. Sci. Lett._, **566**, 116962. It includes some practical updates over the previous version:
- Ability to set calibration functions as lambda function at any point in the calculations. Previously, geologic history calculations required one of the pre-determined calibrations.
- Inclusion of "I-CDES" reference frame as articulated in Bernasoni et al. (2021) _Geochem. Geophys. Geosys._, **22**, e2020GC009588, which should be the "gold standard" for all clumped isotope measurements moving forward.
- Inclusion of the Anderson et al. (2021) _Geophys. Res. Lett._, **48**, e2020GL092069 unified temperature calibration (in I-CDES reference frame).
Also fixed minor bugs and nomenclature issues.