inline iterator& operator++() { ++_iter; return *this; }
inline iterator operator++(int) { iterator tmp(*this); operator++(); return tmp; }
inline bool operator!=(iterator const &i) const { return _iter != i._iter; };
inline bool operator==(iterator const &i) const { return _iter == i._iter; };
inline iterator& operator++() { ++_iter; return *this; }
inline iterator operator++(int) { iterator tmp(*this); operator++(); return tmp; }
inline bool operator!=(iterator const &i) const { return _iter != i._iter; };
inline bool operator==(iterator const &i) const { return _iter == i._iter; };