Mutable endpoint sequence requirements

A mutable endpoint sequence is a range of endpoints into which an operation, such as the receive_from_multiple operation of a datagram socket, writes the source endpoint of each received datagram.

A type X meets the MutableEndpointSequence requirements if it satisfies the requirements of Destructible (C++Std [destructible]) and CopyConstructible (C++Std [copyconstructible]), and is_shallow_mutable_sequence<X>::value is true, as well as the additional requirements listed below.

In the table below, x denotes a value of type X, or of type R if X is std::reference_wrapper<R>, i denotes an iterator in the range [x.begin(),x.end()), and e denotes *i, or (*i).get() if *i is a std::reference_wrapper.

Table 28. MutableEndpointSequence requirements

expression	return type	assertion/note pre/post-condition
`x.begin()` `x.end()`	A type meeting the requirements for forward iterators (C++Std [forward.iterators]).	[`x.begin()`,`x.end()`) is a valid range. The range may be traversed more than once.
`e`	A type satisfying the `Endpoint` requirements.	`e` must be modifiable. On completion, holds the source endpoint of the corresponding datagram.