local({
  previous_options <- options(warn = 2, digits = 8, stringsAsFactors = FALSE)
  on.exit(options(previous_options), add = TRUE)
  check_counts <- function(x, allow_missing = FALSE, allow_empty = FALSE) {
    if (!(is.integer(x) || is.double(x)) || is.object(x) || !is.null(dim(x))) {
      stop("Use a plain numeric vector")
    }
    if (length(x) > 256L || (!allow_empty && length(x) == 0L)) {
      stop("Use 1..256 counts unless empty input is explicitly allowed")
    }
    if (any(is.nan(x)) || (!allow_missing && anyNA(x))) {
      stop("Missing or undefined counts are not allowed here")
    }
    observed <- x[!is.na(x)]
    if (any(!is.finite(observed)) || any(observed < 0) ||
        any(observed > 1000000) || any(observed != floor(observed))) {
      stop("Counts must be finite whole numbers from 0 to 1000000")
    }
    invisible(x)
  }

  new_room_report <- function(rooms, totals) {
    check_counts(totals, allow_empty = TRUE)
    if (!is.character(rooms) || anyNA(rooms) ||
        any(!nzchar(trimws(rooms))) || anyDuplicated(rooms) ||
        length(rooms) != length(totals)) {
      stop("Use one unique non-empty room name per total")
    }
    structure(list(room = rooms, total = as.numeric(totals)), class = "room_report")
  }

  print.room_report <- function(x, ...) {
    cat("rooms:", length(x$room), "total visits:", sum(x$total), "\n")
    invisible(x)
  }

  report <- new_room_report(c("East", "West"), c(18, 26))
  print(report)
  invisible(NULL)
})