Used if you want to change language in test expression in a unitizer when
the actual results of running the expressions is unchanged. This is useful
if you decided to rename functions, etc., without having to re-run the entire
unitize process since unitize matches tests based on
expressions.
logical(1L) whether to run in interactive mode (
request user input when needed) or not (error if user input is required,
e.g. if all tests do not pass).
interactive.only
logical(1L) set to FALSE if you want to allow this to
run in non-interactive mode, but warnings will be suppressed and will
proceed without prompting, obviously...