p:choose-040 (AB)

The pipeline

<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error"
                xmlns:p="http://www.w3.org/ns/xproc"
                xmlns:t="http://xproc.org/ns/testsuite/3.0"
                xmlns:xs="http://www.w3.org/2001/XMLSchema" version="3.0">
   <p:output port="result"/>
   <p:variable name="selector" select="false()"
               as="xs:boolean"/>
   <p:identity>
      <p:with-input>
         <doc1/>
         <doc2/>
      </p:with-input>
   </p:identity>
   <p:choose>
      <p:when test="count(collection())=2"
              collection="{not($selector)}">
         <p:identity>
            <p:with-input>
               <correct/>
            </p:with-input>
         </p:identity>
      </p:when>
   </p:choose>
</p:declare-step>