Variables catalogs are generally loaded lazily, but this function allows you to force them to be loaded once.
A crunch dataset
A dataset with it's variable catalogs filled in
forceVariableCatalog() function is probably most useful when writing tests
because it allows you to be more certain about when API calls are made.
Another situation where you may care about when API calls for loading
the variables are made is when you are loading many datasets at the same
time (~15+) and referring to their variables later. In this situation,
it can be faster to turn off the variables catalog with the option
crunch.lazy.variable.catalog because there is a limit to the number of
datasets your user can hold open at the same time and so at some point the server
will have to unload and then reload the datasets. However, it's probably even faster
if you are able to alter your code so that it operates on datasets sequentially.