public static UArrayAccess create(UExpression arrayExpr, UExpression indexExpr) {
    return new AutoValue_UArrayAccess(arrayExpr, indexExpr);
  }
@Test
  public void unify() {
    UExpression arrayIdent = mock(UExpression.class);
    when(arrayIdent.unify(ident("array"), isA(Unifier.class))).thenReturn(Choice.of(unifier));
    assertUnifies("array[5]", UArrayAccess.create(arrayIdent, ULiteral.intLit(5)));
  }