### Question:
FunctionDefinitionBase implements FunctionDefinition { @Override public boolean returnsBag() { return returnsBag; } 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 testReturnsBag() { FunctionDefinition fdNotBag = StdFunctions.FD_BOOLEAN_EQUAL; assertFalse(fdNotBag.returnsBag()); FunctionDefinitionBag<?> fdBag = (FunctionDefinitionBag<?>) StdFunctions.FD_STRING_BAG; assertTrue(fdBag.returnsBag()); }