[C++] cast away this ptr's pointed object's constness

[reddit] const away this ptr pointed object's constness.

auto container_type::lower_bound(const string &s) -> iterator {
    auto it = const_cast<const container_type *const>(this)->lower_bound(s);
    return underlying_container.erase(it, it); // Some standard container of strings that container_type encapsulates.
}

auto container_type::lower_bound(const string &s) const -> const_iterator {
    return lower_bound(underlying_container.cbegin(), underlying_container.cend(), s);
}