24 Ranges library [ranges]

24.6 Range factories [range.factories]

24.6.2 Single view [range.single]

24.6.2.1 Overview [range.single.overview]

single_­view produces a View that contains exactly one element of a specified value.
[Example
:
single_view s{4};
for (int i : s)
  cout << i; // prints 4
end example
]