public static UAssignOp create(UExpression variable, Kind operator, UExpression expression) {
    checkArgument(
        TAG.containsKey(operator),
        "Tree kind %s does not represent a compound assignment operator",
        operator);
    return new AutoValue_UAssignOp(variable, operator, expression);
  }
@Test
  public void serialization() {
    SerializableTester.reserializeAndAssert(
        UAssignOp.create(UFreeIdent.create("x"), Kind.PLUS_ASSIGNMENT, ULiteral.intLit(2)));
  }