$ perl -Mstrict -e '$FileToOpen=myfile.xlsx;'
Global symbol "$FileToOpen" requires explicit package name (did you forget to declare "my $FileToOpen"?) at -e line 1.
Bareword "myfile" not allowed while "strict subs" in use at -e line 1.
Bareword "xlsx" not allowed while "strict subs" in use at -e line 1.
Execution of -e aborted due to compilation errors.