### Question:
Optionality { public static boolean is_optional(DataType dt) { Ensure.not_null(dt); return (dt instanceof OptionalDataType); } private  Optionality(); static boolean is_optional(DataType dt); static boolean is_optional(DataValue dv); static DataType unoptionalize(DataType dt); static DataType deep_unoptionalize(DataType dt); static DataValue unoptionalize(DataValue dv); static DataValue deep_unoptionalize(DataValue dv); static DataValue optionalize(DataValue v, DataType dt); static boolean is_optional_of(DataType opt, DataType inner); static boolean is_deep_optional_of(DataType opt, DataType inner);  }### Answer:
@Test public void detects_optional_data_type() throws Exception { assertTrue(Optionality.is_optional(m_odt)); }
@Test public void detects_non_optional_data_type() throws Exception { assertFalse(Optionality.is_optional(m_dt)); }
@Test public void detects_optional_data_value() throws Exception { assertTrue(Optionality.is_optional(m_odv)); }
@Test public void detects_non_optional_data_value() throws Exception { assertFalse(Optionality.is_optional(m_dv)); }