code: def DocbookHtml(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_HTML', ['html','docbook.xsl'])
  
      # Setup builder
      __builder = __select_builder(__lxml_builder, __libxml2_builder, __xsltproc_builder)
      
      # Create targets
      result = []
      for t,s in zip(target,source):
          r = __builder.__call__(env, __ensure_suffix(t,'.html'), s, **kw)
          env.Depends(r, kw['DOCBOOK_XSL'])
          result.extend(r)
  
      return result
docs: A pseudo-Builder, providing a Docbook toolchain for HTML output.