Running examples in 'simmer.plot-Ex.R' failed
The error most likely occurred in:

> ### Name: plot.mon
> ### Title: Plot Methods for 'simmer' Monitoring Statistics
> ### Aliases: plot.mon plot.arrivals plot.mon plot.attributes plot.mon
> ###   plot.resources plot.mon
> 
> ### ** Examples
> 
> t0 <- trajectory("my trajectory") %>%
+   ## add an intake activity
+   seize("nurse", 1) %>%
+   timeout(function() rnorm(1, 15)) %>%
+   release("nurse", 1) %>%
+   ## add a consultation activity
+   seize("doctor", 1) %>%
+   timeout(function() rnorm(1, 20)) %>%
+   release("doctor", 1) %>%
+   ## add a planning activity
+   seize("administration", 1) %>%
+   timeout(function() rnorm(1, 5)) %>%
+   release("administration", 1)
> 
> env <- simmer("SuperDuperSim") %>%
+   add_resource("nurse", 1) %>%
+   add_resource("doctor", 2) %>%
+   add_resource("administration", 1) %>%
+   add_generator("patient", t0, function() rnorm(1, 10, 2)) %>%
+   run(until=80)
> 
> resources <- get_mon_resources(env)
> arrivals <- get_mon_arrivals(env)
> 
> plot(resources, metric="usage", "doctor", items = "server", steps = TRUE)
Error in namespaceExport(ns, exports) : 
  undefined exports: %s!=%, %s!==%, %s+%, %s<%, %s<=%, %s==%, %s===%, %s>%, %s>=%, %stri!=%, %stri!==%, %stri+%, %stri<%, %stri<=%, %stri==%, %stri===%, %stri>%, %stri>=%, stri_datetime_add<-, stri_sub<-, stri_subset<-, stri_subset_charclass<-, stri_subset_coll<-, stri_subset_fixed<-, stri_subset_regex<-, stri_c, stri_c_list, stri_cmp, stri_cmp_eq, stri_cmp_equiv, stri_cmp_ge, stri_cmp_gt, stri_cmp_le, stri_cmp_lt, stri_cmp_neq, stri_cmp_nequiv, stri_compare, stri_conv, stri_count, stri_count_boundaries, stri_count_charclass, stri_count_coll, stri_count_fixed, stri_count_regex, stri_count_words, stri_datetime_add, stri_datetime_create, stri_datetime_fields, stri_datetime_format, stri_datetime_fstr, stri_datetime_now, stri_datetime_parse, stri_datetime_symbols, stri_detect, stri_detect_charclass, stri_detect_coll, stri_detect_fixed, stri_detect_regex, stri_dup, stri_duplicated, stri_duplicated_any, stri_enc_detect, stri_enc_detect2, stri_enc_fromutf32, stri_enc_get, stri_enc_inf
Calls: <Anonymous> ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
Execution halted