anchor.diff:    closeLog = mkDerivation {
       name = "silent";
       buildCommand = ''
  +      touch $out
         exec > /dev/null 2>&1
         sleep 1000000000
       '';
  
positive.code:   infiniteLoop = mkDerivation {
      name = "timeout";
      buildCommand = ''
        echo "‘timeout’ builder entering an infinite loop"
        while true ; do echo -n .; done
      '';
  
negative.code:   silent = mkDerivation {
      name = "silent";
      buildCommand = ''
        touch $out
        sleep 60
      '';
    };
  