public function testCompareSequences()
 {
     $seq1 = new Sequence('foo', 1, 1);
     $seq2 = new Sequence('foo', 1, 2);
     $seq3 = new Sequence('foo', 2, 1);
     $c = new Comparator();
     $this->assertTrue($c->diffSequence($seq1, $seq2));
     $this->assertTrue($c->diffSequence($seq1, $seq3));
 }