The derive preprocessor function does not (fully) support lazy derivation of the following variables

• toz - used in recipe_perfmetrics_CMIP5.yml, recipe_eyring06jgr.yml
• xco2 - used in recipe_gier2020bg.yml
• xch4 - used in recipe_mpqb_xch4.yml
• co2s - used in schlund20jgr/recipe_*.yml, recipe_gier2020bg.yml, recipe_wenzel16nat.yml
• uajet - used in recipe_wenzel16jclim.yml
• vegfrac - not used in any recipe Lazy derivation of vegfrac #2452

All of these derivation functions can also be 'tested' using examples/recipe_preprocessor_derive_test.yml.

Previous discussion on this topic in #42.