|  | 
            Query the current value of the allocator
            property.
          
constexpr Allocator query( execution::allocator_t< void > ) const;
            Do not call this function directly. It is intended for use with the
            query
            customisation point.
          
For example:
asio::system_executor ex; auto alloc = asio::query(ex, asio::execution::allocator);