...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Returns the allocator associated with this object.
allocator_type get_allocator() const;
If a class derived from boost::beast::async_base
is a completion handler,
then the object returned from this function will be used as the associated
allocator of the derived class.