Query the current value of the blocking property.

constexpr execution::blocking_t query(
    execution::blocking_t ) const;

Do not call this function directly. It is intended for use with the query customisation point.

For example:

auto ex = my_io_context.get_executor();
if (boost::asio::query(ex, boost::asio::execution::blocking)
      == boost::asio::execution::blocking.always)
  ...