code: public void checkInvariants(CallStack frame, Expr... invariants) {
  		for (int i = 0; i != invariants.length; ++i) {
  			RValue.Bool b = executeExpression(BOOL_T, invariants[i], frame);
  			if (b == RValue.False) {
  				// FIXME: need to do more here
  				throw new AssertionError();
  			}
  		}
  	}
docs: Evaluate zero or more conditional expressions, and check whether any is
  false. If so, raise an exception indicating a runtime fault.
  
  @param frame
  @param context
  @param invariants