code: def visit_desc(self):
          
          desc = []
  
          if self.__desc__:
              desc += [self.__desc__]
  
          for node in pe.utils.topological_sort(self._graph)[0]:
              if isinstance(node, LiterateWorkflow):
                  add_desc = node.visit_desc()
                  if add_desc not in desc:
                      desc.append(add_desc)
  
          if self.__postdesc__:
              desc += [self.__postdesc__]
  
          return ''.join(desc)
docs: Builds a citation boilerplate by visiting all workflows
          appending their ``__desc__`` field