 get_numbers(list, index = 0, taken = [])
  return [taken] if index == list.size

  get_numbers(list, index+1, taken) +
  get_numbers(list, index+1, taken + [list[index]])
end

get_numbers([1,2,3])
</code></pre>
      </div>
    </section>

    <section>
      <h2>Table</h2>
      <div class="markdown">
        <table>
          <thead>
            <tr>
              <th align="center">Header</th>
              <th>Header</th>
              <th align="left">Header</th>
              <th align="right">Header