friend constexpr bool operator==(
const istreambuf_iterator& lhs, const istreambuf_iterator& rhs) noexcept {
return lhs.equal(rhs);
}
bool operator == (const istreambuf_iterator<charT, traits>& lhs,
const istreambuf_iterator<charT, traits>& rhs)
{
return lhs.equal(rhs);
}
explicit constexpr pointer(const istreambuf_iterator& i)
noexcept(is_nothrow_move_constructible<charT>::value) :
keep_{i.get()} {}
