<tr>
      <th>weight_column</th>
      <td><p>A string or a <code>_NumericColumn</code> created by
<code>column_numeric</code> defining feature column representing
weights. It is used to down weight or boost examples during training. It
will be multiplied by the loss of the example. If it is a string, it is
used as a key to fetch weight tensor from the <code>features</code>. If it is a
<code>_NumericColumn</code>, raw tensor is fetched by key <code>weight_column$key</code>, then
<code>weight_column$normali