p:with-option 010 (AB)

The pipeline

<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" xmlns:xs="http://www.w3.org/2001/XMLSchema" version="3.0">
   <p:output port="result"/>
   <p:add-attribute match="doc1" attribute-name="att">
      <p:with-input>
         <doc1/>
      </p:with-input>
      <p:with-option name="attribute-value" select="/doc" collection="{true()}">
         <doc>value</doc>
      </p:with-option>
   </p:add-attribute>
</p:declare-step>