...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
The type of buffer returned when dereferencing an iterator.
using value_type = implementation-defined;
If every buffer sequence in the view is a MutableBufferSequence,
then value_type
will be
boost::asio::mutable_buffer
. Otherwise, value_type
will be boost::asio::const_buffer
.