std::set

You must implement a Set class that supports the following code snippets and produces the specified output.

#include <algorithm>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <string_view>

template<typename T> class Set;

template<typename T>
std::ostream& operator<<(std::ostream& out, const Set<T>& set)
{
    if (set.empty())
        return out << "{}";
    out << "{ " << *set.begin();
    std::for_each(std::next(set.begin()), set.end(), [&out](const T& element)
    {
        out << ", " << element;
    });
    return out << " }";
}

int main()
{
    Set<int> set{1, 5, 3};
    std::cout << set << '\n';

    set.insert(2);
    std::cout << set << '\n';

    set.erase(1);
    std::cout << set << "\n\n";

    Set<int> keys{3, 4};
    for (int key : keys)
    {
        if (set.contains(key))
            std::cout << set << " does contain " << key << '\n';
        else
            std::cout << set << " doesn't contain " << key << '\n';
    }
    std::cout << '\n';

    std::string_view word = "element";
    Set<char> characters(word.begin(), word.end());
    std::cout << "There are " << characters.size() << " unique characters in "
              << std::quoted(word) << ":\n" << characters << '\n';
}

Output

{ 1, 3, 5 }
{ 1, 2, 3, 5 }
{ 2, 3, 5 }

{ 2, 3, 5 } does contain 3
{ 2, 3, 5 } doesn't contain 4

There are 5 unique characters in "element":
{ e, l, m, n, t }

You may not use std::set or modify the given code.