Exchange the contents of the specified hash maps.
Declared in <bslstp_hashmap.h>
template<
class _Key,
class _Tp,
class _HashFcn,
class _EqualKey,
class _Alloc>
void
swap(
hash_map<_Key, _Tp, _HashFcn, _EqualKey, _Alloc>& lhs,
hash_map<_Key, _Tp, _HashFcn, _EqualKey, _Alloc>& rhs);