cpp/ranges/elements view

@1@ Accepts a of tuple-like values, and issues a view with a value type of the -th element of the adapted view's value-type.

@2@ Every specialization of is a. The expression is expression-equivalent to  for any suitable subexpression  and constant expression.

@3@ Ensures that the elements of the underlying view are tuple-like values.

@4@ Ensures that dangling references cannot be returned.

models the concepts, , , , , and when the underlying view  models respective concepts.

Helper templates
This specialization of makes  satisfy  when the underlying view satisfies it.