depends 004 (AB)

The pipeline

<p:declare-step xmlns:acme="http://acme" xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:output port="result"/>
   <p:declare-step type="acme:test">
      <p:output port="result"/>
      <p:identity>
         <p:with-input>
            <inner/>
         </p:with-input>
      </p:identity>
   </p:declare-step>
   <p:identity name="first">
      <p:with-input>
         <doc1/>
      </p:with-input>
   </p:identity>
   <acme:test>
      <p:with-option name="p:depends" select="'first'"/>
   </acme:test>
</p:declare-step>