ARB <- local({
  filename <- "ARB_source.rda"
  candidates <- c(
    system.file("extdata", filename, package = "TTE"),
    file.path("inst", "extdata", filename),
    file.path("..", "inst", "extdata", filename),
    file.path(getwd(), "inst", "extdata", filename),
    file.path(getwd(), "..", "inst", "extdata", filename)
  )
  candidates <- candidates[nzchar(candidates) & file.exists(candidates)]
  if (!length(candidates)) {
    stop("Could not locate the internal ARB data file.", call. = FALSE)
  }
  env <- new.env(parent = baseenv())
  loaded <- load(candidates[[1L]], envir = env)
  if (length(loaded) != 1L) {
    stop("The internal ARB data file is invalid.", call. = FALSE)
  }
  env[[loaded[[1L]]]]
})
