code: def _format_config_nodes(self, modulename, classname):
          
          fullname = '{0}.{1}.config'.format(modulename, classname)
  
          # The signature term
          desc_sig_node = desc_signature()
          desc_sig_node['module'] = modulename
          desc_sig_node['class'] = classname
          desc_sig_node['fullname'] = fullname
  
          prefix = 'attribute'
          desc_sig_node += desc_annotation(prefix, prefix)
          desc_sig_name_node = desc_addname('config', 'config')
          # Fakes the look of a cross reference.
          desc_sig_name_node['classes'].extend(['xref', 'py'])
          desc_sig_node += desc_sig_name_node
  
          # The content is the one-sentence summary.
          summary_text = (
              'Access configuration fields and retargetable subtasks.'
          )
          content_node_p = nodes.paragraph(text=summary_text)
          content_node = desc_content()
          content_node += content_node_p
  
          desc_node = desc()
          desc_node['noindex'] = True
          desc_node['domain'] = 'py'
          desc_node['objtype'] = 'attribute'
          desc_node += desc_sig_node
          desc_node += content_node
          return desc_node
docs: Create a ``desc`` node summarizing the config attribute
  
          The ``config`` attribute is not statically available from a task class.
          This method manually creates a signature and docstring for the
          config attribute.