A class or pointer type
satisfies the requirements of an output iterator
if X satisfies the Cpp17Iterator requirements ([iterator.iterators])
and the expressions in Table 77
are valid and have the indicated semantics.
Table 77 — Cpp17OutputIterator requirements (in addition to Cpp17Iterator)
*r = o
result is not used
Remarks: After this operation r is not required to be dereferenceable.