code: private Term evalIsLiteral(Function term) {
  		Term innerTerm = term.getTerm(0);
  		if (innerTerm instanceof Function) {
  			Function function = (Function) innerTerm;
  			return termFactory.getBooleanConstant(function.isDataTypeFunction());
  		} 
  		else {
  			return term;
  		}
  	}
docs: /*
  Expression evaluator for isLiteral() function