5 #include <boost/range/algorithm/find.hpp> 
   10   template <
typename T, 
typename Allocator = std::allocator<T>>
 
   13   has(
const std::deque<T, Allocator>& s, 
const T& e)
 
   15     return boost::find(s, e) != std::end(s);
 
ATTRIBUTE_PURE bool has(const boost::container::flat_set< Key, Compare, Allocator > &s, const Key &e)
Whether e is member of s.