- STRUCTURE
- SYNOPSIS
- Theorem-tactical which always fails. 
- DESCRIPTION
- When applied to a theorem-tactic and a theorem, the theorem-tactical
NO_THEN always fails with string `NO_THEN`. 
- FAILURE
- Always fails when applied to a theorem-tactic and a theorem (note that it
never gets as far as being applied to a goal!) 
- USES
- Writing compound tactics or tacticals. 
- SEEALSO