ctive frameworks.
For this specific case, the failure/error is <code>Never</code>, meaning that this subject can&rsquo;t emit error.
This abstraction uses concept similar to type-erasure or protocol witness pattern, wrapping the behaviour of concrete implementations and
delegating to them once the wrapper funcions are called.</p>

                      </div>
                      <div class="declaration">
                        <h4>Declaration</h4>
                        <div class="language">
          