namespace std {
template <class charT, class traits>
basic_istream<charT,traits>& ws(basic_istream<charT,traits>& is);
}
Effects: Behaves as an unformatted input function (as described in [istream.unformatted], paragraph 1), except that it does not count the number of characters extracted and does not affect the value returned by subsequent calls to is.gcount(). After constructing a sentry object extracts characters as long as the next available character c is whitespace or until there are no more characters in the sequence. Whitespace characters are distinguished with the same criterion as used by sentry::sentry ([istream::sentry]). If ws stops extracting characters because there are no more available it sets eofbit, but not failbit.
Returns: is.