### Question:
RangeConverter { @Nullable public static String tokenReference(@Nullable Token token) { if (token == null) { return null; } return format(token.textRange()); } private  RangeConverter(); @Nullable static String format(@Nullable TextRange range); @Nullable static TextRange parse(@Nullable String value); @Nullable static String tokenReference(@Nullable Token token); @Nullable static Token resolveToken(TreeMetaDataProvider metaDataProvider, @Nullable String tokenReference); static String metaDataReference(Tree tree); static TreeMetaData resolveMetaData(TreeMetaDataProvider metaDataProvider, String metaDataReference); @Nullable static String treeReference(@Nullable Tree tree); @Nullable static T resolveNullableTree(Tree parent, @Nullable String treeReference, Class<T> childClass);  }### Answer:
@Test public void token_reference() { Token token = otherToken(3, 7, "foo"); assertThat(RangeConverter.tokenReference(token)).isEqualTo("3:7:3:10"); assertThat(RangeConverter.tokenReference(null)).isNull(); }