### Question:
VariantStats { public static boolean isTransition(String refAllele, String altAllele) { switch (refAllele.toUpperCase()) { case "C": return altAllele.equalsIgnoreCase("T"); case "T": return altAllele.equalsIgnoreCase("C"); case "A": return altAllele.equalsIgnoreCase("G"); case "G": return altAllele.equalsIgnoreCase("A"); default: return false; } } VariantStats(String cohortId);  VariantStats();  VariantStats(org.opencb.biodata.models.variant.avro.VariantStats other);  VariantStats(float maf, float mgf, String mafAllele, String mgfGenotype,
                        int missingAlleleCount, int missingGenotypeCount); org.opencb.biodata.models.variant.avro.VariantStats getImpl(); VariantStats setCohortId(String cohortId); String getCohortId(); Integer getAlleleCount(); void setAlleleCount(Integer value); Integer getSampleCount(); void setSampleCount(Integer value); Integer getFileCount(); void setFileCount(Integer value); Integer getRefAlleleCount(); void setRefAlleleCount(Integer value); Integer getAltAlleleCount(); void setAltAlleleCount(Integer value); Map<String, Integer> getGenotypeCount(); void setGenotypeCount(Map<String, Integer> value); Map<String, Float> getGenotypeFreq(); void setGenotypeFreq(Map<String, Float> value); Integer getMissingAlleleCount(); void setMissingAlleleCount(Integer value); Integer getMissingGenotypeCount(); void setMissingGenotypeCount(Integer value); Float getRefAlleleFreq(); void setRefAlleleFreq(Float value); Float getAltAlleleFreq(); void setAltAlleleFreq(Float value); Float getMaf(); void setMaf(Float value); Float getMgf(); void setMgf(Float value); String getMafAllele(); void setMafAllele(String value); String getMgfGenotype(); void setMgfGenotype(String value); VariantStats addGenotype(Genotype g); VariantStats addGenotype(Genotype g, int addedCount); VariantStats addGenotype(Genotype g, int addedCount, boolean normalize); VariantStats addGenotype(String genotype); VariantStats addGenotype(String genotype, int addedCount); Map<String, Integer> getFilterCount(); void setFilterCount(Map<String, Integer> value); Map<String, Float> getFilterFreq(); void setFilterFreq(Map<String, Float> value); Float getQualityAvg(); void setQualityAvg(Float value); Integer getQualityCount(); void setQualityCount(Integer value); static boolean isTransition(String refAllele, String altAllele); static boolean isTransversion(String refAllele, String altAllele); @Override String toString(); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test public void transitionTest() { assertTrue(VariantStats.isTransition("A", "G")); assertTrue(VariantStats.isTransition("C", "T")); assertTrue(VariantStats.isTransition("G", "A")); assertTrue(VariantStats.isTransition("T", "C")); assertFalse(VariantStats.isTransition("A", "N")); assertFalse(VariantStats.isTransition("C", "N")); assertFalse(VariantStats.isTransition("G", "N")); assertFalse(VariantStats.isTransition("T", "N")); assertFalse(VariantStats.isTransition("A", "")); assertFalse(VariantStats.isTransition("C", "")); assertFalse(VariantStats.isTransition("G", "")); assertFalse(VariantStats.isTransition("T", "")); assertFalse(VariantStats.isTransition("", "A")); assertFalse(VariantStats.isTransition("", "C")); assertFalse(VariantStats.isTransition("", "G")); assertFalse(VariantStats.isTransition("", "T")); }