@Test
public void accept() throws Exception {

  new StandardVisitor() {
    @Override
    public void visitMemberLookupExpr(MemberLookupExpr memberLookupExpr) {
      super.visitMemberLookupExpr(memberLookupExpr);
      assertEquals("foo", memberLookupExpr.getMember());
      assertTrue(memberLookupExpr.getStructure() instanceof VariableIdentifierExpr);
      assertEquals("v", ((VariableIdentifierExpr) memberLookupExpr.getStructure()).getName());
    }
  }.visit(new MemberLookupExpr(new VariableIdentifierExpr("v"), "foo"));
}