Since lists allow fast insertion and erasing from the middle of a list, certain
operations are provided specifically for them.
In this subclause,
arguments for a template parameter
shall meet the corresponding requirements in [algorithms.requirements].
The semantics of i + n
and i - n
is an iterator into the list and n
is an integer,
are the same as those of next(i, n)
and prev(i, n)
the definitions and requirements in [alg.sorting]