Theory_Data.extend is obsolete since Isabelle/efb7fd4a6d1f but still present in the signature to allow for explicit checking of its required behaviour as identity function.
After the next (or a later) release, it can be discontinued altogether.
Theory_Data.extend is obsolete since Isabelle/efb7fd4a6d1f but still present in the signature to allow for explicit checking of its required behaviour as identity function.
After the next (or a later) release, it can be discontinued altogether.