
<td align="left"><code>vctrs::unspecified(1)</code></td>
<td align="left">???</td>
</tr>
<tr class="odd">
<td align="left"></td>
<td align="left">vctrs_list_of</td>
<td align="left"><code>vctrs::list_of(c(1L))</code></td>
<td align="left">list<int></td>
</tr>
<tr class="even">
<td align="left"></td>
<td align="left">vctrs_vctr</td>
<td align="left"><code>vctrs::new_vctr(1L)</code></td>
<td align="left">vctrs_vc</td>
</tr>
<tr class="odd">
<td align="left"></td>
<td align="left">vctrs_partial_factor</td>
<t