use Data::Compare;
# this test is called "Scalar Cross" in both the Data::BFDump and Data::Stream test sets
my ($a,$x,$y)=([]); 
$x=\$y; 
$y=\$x; 
$a->[0]=\$a->[1]; 
$a->[1]=\$a->[0]; 
print Compare([$x,$y],$a); # infinte loop