### Question:
FunctionDefinitionBase implements FunctionDefinition { @Override public Identifier getId() { return this.id; } protected  FunctionDefinitionBase(Identifier idIn, DataType<O> returnDataTypeIn, DataType<I> argumentDataTypeIn, boolean returnsBagIn); String getShortFunctionId(); String getShortDataTypeId(Identifier identifier); Status getFunctionStatus(Status originalStatus); @Override Identifier getId(); @Override Identifier getDataTypeId(); DataType<O> getDataType(); DataType<I> getDataTypeArgs(); @Override boolean returnsBag();  }### Answer:
@Test public void testGetId() { FunctionDefinition fd = StdFunctions.FD_STRING_EQUAL; Identifier id = fd.getId(); assertTrue(XACML3.ID_FUNCTION_STRING_EQUAL.stringValue().equals(id.stringValue()) ); }