code: def DocbookSlidesPdf(env, target, source=None, *args, **kw):
      
      # Init list of targets/sources
      target, source = __extend_targets_sources(target, source)
  
      # Init XSL stylesheet
      __init_xsl_stylesheet(kw, env, '$DOCBOOK_DEFAULT_XSL_SLIDESPDF', ['slides','fo','plain.xsl'])
  
      # Setup builder
      __builder = __select_builder(__lxml_builder, __libxml2_builder, __xsltproc_builder)
  
      # Create targets
      result = []
      for t,s in zip(target,source):
          t, stem = __ensure_suffix_stem(t, '.pdf')
          xsl = __builder.__call__(env, stem+'.fo', s, **kw)
          env.Depends(xsl, kw['DOCBOOK_XSL'])        
          result.extend(xsl)
          result.extend(__fop_builder.__call__(env, t, xsl, **kw))
  
      return result
docs: A pseudo-Builder, providing a Docbook toolchain for PDF slides output.