>> c.pl:1: require "a.pl";
>> a.pl:1: use strict;
...
>> a.pl:2: use warnings;
...
>> c.pl:2: print "$database\n";
>> c.pl:3: require "b.pl";
>> b.pl:1: use strict;
...
>> b.pl:2: use warnings;
...
>> c.pl:4: print "$database\n";
>> c.pl:5: require "a.pl";
>> c.pl:6: print "$database\n";