I have to following code using bg_subtest and i would
like know which sub_test is executed first, or i would
like to exit once any one of subtest completed

for (my $1 = 0 ; $i < $10 ; $i++) { 
    bg_subtest $self->tap("Write multiple files") => 
      sub { 
     exec("dd if=/dev/random of=/tmp/file${i} bs=1024  count =1000"); 
    }    
}
bg_subtest_wait();
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In the above code i would like file is written first?