old_contents: class DataFlowException(Exception):
      """Base class for all exceptions.
  
      Only to be invoked when only a more specific error is not available.
  
      """
  
  
  class ConfigurationError(DataFlowException):
      """Raised when the DataFlowKernel receives an invalid configuration.
      """
  
  
  class DuplicateTaskError(DataFlowException):
      """Raised by the DataFlowKernel when it finds that a job with the same task-id has been launched before.
      """
  
  
  class MissingFutError(DataFlowException):
      """Raised when a particular future is not found within the dataflowkernel's datastructures.
  
      Deprecated.
      """
  
  
  class BadCheckpoint(DataFlowException):
      """Error raised at the end of app execution due to missing output files.
  
      Args:
           - reason
  
      Contains:
      reason (string)
      dependent_exceptions
      """
  
      def __init__(self, reason):
          self.reason = reason
  
      def __repr__(self):
          return self.reason
  
      def __str__(self):
          return self.__repr__()
  
  
  class DependencyError(DataFlowException):
      """Error raised at the end of app execution due to missing output files.
  
      Args:
           - dependent_exceptions: List of exceptions
           - task_id: Identity of the task failed task
           - outputs ?
  
      Contains:
      reason (string)
      dependent_exceptions
      """
  
      def __init__(self, dependent_exceptions, task_id, outputs):
          self.dependent_exceptions = dependent_exceptions
          self.task_id = task_id
          self.outputs = outputs
  
      def __repr__(self):
          return "[{}] Dependency Failure from :{}".format(self.task_id,
                                                           self.dependent_exceptions)
  
      def __str__(self):
          return self.__repr__()
  
new_contents: class DataFlowException(Exception):
      """Base class for all exceptions.
  
      Only to be invoked when only a more specific error is not available.
  
      """
  
  
  class ConfigurationError(DataFlowException):
      """Raised when the DataFlowKernel receives an invalid configuration.
      """
  
  
  class DuplicateTaskError(DataFlowException):
      """Raised by the DataFlowKernel when it finds that a job with the same task-id has been launched before.
      """
  
  
  class MissingFutError(DataFlowException):
      """Raised when a particular future is not found within the dataflowkernel's datastructures.
  
      Deprecated.
      """
  
  
  class BadCheckpoint(DataFlowException):
      """Error raised at the end of app execution due to missing output files.
  
      Args:
           - reason
  
      Contains:
      reason (string)
      dependent_exceptions
      """
  
      def __init__(self, reason):
          self.reason = reason
  
      def __repr__(self):
          return self.reason
  
      def __str__(self):
          return self.__repr__()
  
  
  class DependencyError(DataFlowException):
      """Error raised at the end of app execution due to missing output files.
  
      Args:
           - dependent_exceptions: List of exceptions
           - task_id: Identity of the task failed task
           - outputs ?
  
      Contains:
      reason (string)
      dependent_exceptions
      """
  
      def __init__(self, dependent_exceptions, task_id, outputs):
          self.dependent_exceptions = dependent_exceptions
          self.task_id = task_id
          self.outputs = outputs
  
      def __repr__(self):
          return "[{}] Dependency failure from: {}".format(self.task_id,
                                                           self.dependent_exceptions)
  
      def __str__(self):
          return self.__repr__()
  
subject: Change dependency failure formatting