code: def get_job_definitions(self, identifier):
          
          result = []
          env = self.get_job_definition_by_arn(identifier)
          if env is not None:
              result.append(env)
          else:
              for value in self._job_definitions.values():
                  if value.name == identifier:
                      result.append(value)
  
          return result
docs: Get job defintiion by name or ARN
          :param identifier: Name or ARN
          :type identifier: str
  
          :return: Job definition or None
          :rtype: list of JobDefinition