ostreambuf_iterator(ostream_type& s) noexcept;
Preconditions: 
s.rdbuf()
is not a null pointer
. Effects: Initializes 
sbuf_ with 
s.rdbuf(). ostreambuf_iterator(streambuf_type* s) noexcept;
Preconditions: 
s
is not a null pointer
. Effects: Initializes 
sbuf_ with 
s.