libboost-contract1.71-dev 1.71.0-6ubuntu4 (armhf binary) in ubuntu focal

 This package forms part of the Boost C++ Libraries collection.
 .
 All contract programming features are supported: Subcontracting,
 class invariants, postconditions (with old and return values),
 preconditions, customizable actions on assertion failure (e.g.,
 terminate or throw), optional compilation and checking of assertions,
 etc.