title: merging 2 data frames that doesnt have a shared column
body: <p>I am having some trouble with merging 2 data frames that doesn't have any same column.
  I have 2 data frames and I want to combine them (they both have the same row number)</p>
  <p>For example, I have these two data frames:</p>
  <p>A:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th style="text-align: left;">store</th>
  <th style="text-align: center;">red candy</th>
  <th style="text-align: right;">apple</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td style="text-align: left;">first</td>
  <td style="text-align: center;">5</td>
  <td style="text-align: right;">3</td>
  </tr>
  <tr>
  <td style="text-align: left;">second</td>
  <td style="text-align: center;">1</td>
  <td style="text-align: right;">2</td>
  </tr>
  <tr>
  <td style="text-align: left;">third</td>
  <td style="text-align: center;">4</td>
  <td style="text-align: right;">2</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>B:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>yellow candy</th>
  <th>banana</th>
  <th>green candy</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>10</td>
  <td>5</td>
  <td>4</td>
  </tr>
  <tr>
  <td>5</td>
  <td>3</td>
  <td>3</td>
  </tr>
  <tr>
  <td>1</td>
  <td>1</td>
  <td>0</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>and I want to merge them so I will have one data frame looks like this:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th style="text-align: left;">store</th>
  <th style="text-align: center;">red candy</th>
  <th style="text-align: right;">apple</th>
  <th>yellow candy</th>
  <th>banana</th>
  <th>green candy</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td style="text-align: left;">first</td>
  <td style="text-align: center;">5</td>
  <td style="text-align: right;">3</td>
  <td>10</td>
  <td>5</td>
  <td>4</td>
  </tr>
  <tr>
  <td style="text-align: left;">second</td>
  <td style="text-align: center;">1</td>
  <td style="text-align: right;">2</td>
  <td>5</td>
  <td>3</td>
  <td>3</td>
  </tr>
  <tr>
  <td style="text-align: left;">third</td>
  <td style="text-align: center;">4</td>
  <td style="text-align: right;">2</td>
  <td>1</td>
  <td>1</td>
  <td>0</td>
  </tr>
  </tbody>
  </table>
  </div>