nt">TEST-NOT</li>  </ul>  <a class="source-link" href="https://shinmera.com/project/array-utils/blob/e71aaf14be270d4aa1e5ba6fa9319e2de776dda0/utils.lisp#L132">Source</a>  </header> <div class="docstring"><pre>Pushes the element onto the back of the vector and extends if necessary, if it is not already part of the vector.

If TEST is passed, it is used to compare the elements. Defaults to EQL
If TEST-NOT is passed, its complement is used to compare the element.
If KEY is passed, it is used to extract the ele