try to avoid races again (cf. 8c37cb84065f and fd3a36e48b09);
no_document use_thys [
"~~/src/HOL/Library/Countable",
"~~/src/HOL/Library/Monad_Syntax",
"~~/src/HOL/Library/Code_Natural",
"~~/src/HOL/Library/LaTeXsugar"];
use_thys ["Imperative_HOL_ex"];