Returns:;; An iterator pointing to an element with key equivalent to `k`, or `end()` if no such element exists. Notes:;; The `template<class K>` overloads only participate in overload resolution if `Hash::is_transparent` and `Pred::is_transparent` are valid member typedefs. The library assumes that `Hash` is callable with both `K` and `Key` and that `Pred` is transparent. This enables heterogeneous lookup which avoids the cost of instantiating an instance of the `Key` type.
Returns:;; The maximum number of elements the container can hold without rehashing, assuming that no further elements will be erased. Note:;; After construction, rehash or clearance, the container's maximum load is at least `max_load_factor() * bucket_count()`. This number may decrease on erasure under high-load conditions.