This object controls how to load cached environments from languages other
than R (when the chunk option engine is not 'R'). Each
component in this object is a function that takes the current path to the
chunk cache and loads it into the language environment.
cache_enginesAn object of class list of length 5.
The cache engine function has one argument options, a list containing
all chunk options. Note that options$hash is the path to the current
chunk cache with the chunk's hash, but without any file extension, and the
language engine may write a cache database to this path (with an extension).
The cache engine function should load the cache environment and should know the extension appropriate for the language.
See https://github.com/rstudio/reticulate/pull/167 for an implementation of a cache engine for Python.