Defined in header
template< class ForwardIt >
ForwardIt next( ForwardIt it,
Return the nth successor of iterator it.
|n||-||number of elements to advance|
 Return value
The nth successor of iterator it.
 Possible implementation
Although the expression ++c.begin() often compiles, it is not guaranteed to do so: c.begin() is an rvalue expression, and there is no
BidirectionalIterator requirement that specifies that increment of an rvalue is guaranteed to work. In particular, when iterators are implemented as pointers, ++c.begin() does not compile, while std::next(c.begin()) does.
 See also
| decrement an iterator
| advances an iterator by given distance