This function is called 6 times, each each call puts out about
15 tests, with the same set of descriptions, so output a note
at the start of each call showing where we're called from.
$slowr, $slowratet, $slowslow, $slowfastt,
$fastr, $fastratet, $fastslowt, $fastfast)
= @_;
+ note("calling check_graph_consistency from line " . (caller(1))[2]);
my $all_passed = 1;
$all_passed
&= is ($slowc, $slowr, "left col tag should be top row tag");