libboost-coroutine1.71-dev 1.71.0-3 (armhf binary) in ubuntu focal

 This package forms part of the Boost C++ Libraries collection.
 .
 Boost.Coroutine provides templates for generalized subroutines which
 allow multiple entry points for suspending and resuming execution at
 certain locations. It preserves the local state of execution and
 allows re-entering subroutines more than once (useful if state must
 be kept across function calls).
 .
 Coroutines can be viewed as a language-level construct providing a
 special kind of control flow.
 .
 In contrast to threads, which are pre-emptive, coroutine switches are
 cooperative (programmer controls when a switch will happen). The
 kernel is not involved in the coroutine switches.
 .
 The implementation uses Boost.Context for context switching.