docs: def getWorkitem(self, workitem_id, returned_properties=None):
          """Get :class:`rtcclient.workitem.Workitem` object by its id/number
  
          :param workitem_id: the workitem id/number
              (integer or equivalent string)
          :param returned_properties: the returned properties that you want.
              Refer to :class:`rtcclient.client.RTCClient` for more explanations
          :return: the :class:`rtcclient.workitem.Workitem` object
          :rtype: rtcclient.workitem.Workitem
          """
  
          try:
              if isinstance(workitem_id, bool):
                  raise ValueError("Invalid Workitem id")
              if isinstance(workitem_id, six.string_types):
                  workitem_id = int(workitem_id)
              if not isinstance(workitem_id, int):
                  raise ValueError("Invalid Workitem id")
  
              workitem_url = "/".join([self.url,
                                       "oslc/workitems/%s" % workitem_id])
  
              rp = self._validate_returned_properties(returned_properties)
              if rp is not None:
                  req_url = "".join([workitem_url,
                                     "?oslc_cm.properties=",
                                     urlquote(rp)])
              else:
                  req_url = workitem_url
              resp = self.get(req_url,
                              verify=False,
                              proxies=self.proxies,
                              headers=self.headers)
              raw_data = xmltodict.parse(resp.content)
              workitem_raw = raw_data["oslc_cm:ChangeRequest"]
  
              return Workitem(workitem_url,
                              self,
                              workitem_id=workitem_id,
                              raw_data=workitem_raw)
  
          except ValueError:
              excp_msg = "Please input a valid workitem id"
              self.log.error(excp_msg)
              raise exception.BadValue(excp_msg)
          except Exception as excp:
              self.log.error(excp)
              raise exception.NotFound("Not found <Workitem %s>" % workitem_id)