code: def _get_description(self):
          
          ns = {'ns': '{%s}' % BPMN_MODEL_NS}
          desc = (
              self.doc_xpath('.//{ns}collaboration/{ns}documentation'.format(**ns)) or
              self.doc_xpath('.//{ns}process/{ns}documentation'.format(**ns)) or
              self.doc_xpath('.//{ns}collaboration/{ns}participant/{ns}documentation'.format(**ns))
          )
          if desc:
              return desc[0].findtext('.')
docs: Tries to get WF description from 'collabration' or 'process' or 'pariticipant'
          Returns: