Wander Lairson Costa [off-list ref] writes:

Replace inline NotImplementedError raises with a dedicated decorator in
the ltl2ba module. The previous implementation used explicit raise
statements inside abstract method bodies for BinaryOp and UnaryOp
classes, which required maintaining identical boilerplate across seven
different methods that need to be overridden by subclasses.

All stub methods in generator.py have been converted from returning
strings to using the decorator with ellipsis function bodies, which
is the recommended Python style for marking incomplete interface
methods. This ensures that any attempt to use unimplemented
functionality fails fast with a clear exception rather than silently
propagating string values through the code.

The new @not_implemented decorator consolidates this pattern into a
single reusable definition that clearly marks abstract methods while
reducing code duplication. The decorator creates a wrapper that raises
NotImplementedError with the function name, providing the same runtime
behavior with improved maintainability. Method bodies now use the
ellipsis literal instead of pass statements, which is the preferred
Python convention for stub methods according to PEP 8.

Signed-off-by: Wander Lairson Costa <redacted>

Reviewed-by: Nam Cao <redacted>