## Description
User-defined/Built-in KeY sorts are supposed to be accessible from within JML using a `\dl_` escape. However, this does not work within quantified expressions.
### Steps to reproduce
always
```
final class C {
//@ invariant (\forall \dl_Seq c; c == c);
}
```
does not load in KeY.
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* Commit: 7fe4e7dba53801c38716889cec9241488ce31680