code: def updateAttachment(self, oid, attachment_id, file_path):
          
          url = self._url + "/%s/updateAttachment" % oid
          params = {
              "f":"json",
              "attachmentId" : "%s" % attachment_id
          }
          files = {'attachment': file_path }
          res = self._post(url=url,
                               param_dict=params,
                               files=files,
                               securityHandler=self._securityHandler,
                               proxy_port=self._proxy_port,
                               proxy_url=self._proxy_url)
          return self._unicode_convert(res)
docs: updates an existing attachment with a new file
              Inputs:
                 oid - string/integer - Unique record ID
                 attachment_id - integer - Unique attachment identifier
                 file_path - string - path to new attachment
              Output:
                 JSON response