depends 121 (AB)

The pipeline

<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:output port="result"/>
   <p:variable name="episode" select="p:system-property('p:episode')"/>
   <p:file-create-tempfile delete-on-exit="true"/>
   <p:variable name="path" select="*:result/text()"/>
   <p:try name="identity">
      <p:error code="some-error"/>
      <p:catch>
         <p:identity depends="storer">
            <p:with-input select="doc($path)">
               <context/>
            </p:with-input>
         </p:identity>
      </p:catch>
   </p:try>
   <p:sink/>
   <p:store href="{$path}" name="storer">
      <p:with-input>
         <doc>{$episode}</doc>
      </p:with-input>
   </p:store>
   <p:choose>
      <p:with-input pipe="@identity"/>
      <p:when test="doc/text() = $episode">
         <p:identity>
            <p:with-input>
               <success/>
            </p:with-input>
         </p:identity>
      </p:when>
      <p:otherwise>
         <p:identity>
            <p:with-input>
               <failure/>
            </p:with-input>
         </p:identity>
      </p:otherwise>
   </p:choose>
</p:declare-step>