parameters: (self,
              idempotence_key='',
              queue_name='default',
              base_path='/_ah/pipeline',
              return_task=False,
              countdown=None,
              eta=None)
docstring: Starts a new instance of this pipeline.
  
      Args:
        idempotence_key: The ID to use for this Pipeline and throughout its
          asynchronous workflow to ensure the operations are idempotent. If
          empty a starting key will be automatically assigned.
        queue_name: What queue this Pipeline's workflow should execute on.
        base_path: The relative URL path to where the Pipeline API is
          mounted for access by the taskqueue API or external requests.
        return_task: When True, a task to start this pipeline will be returned
          instead of submitted, allowing the caller to start off this pipeline
          as part of a separate transaction (potentially leaving this newly
          allocated pipeline's datastore entities in place if that separate
          transaction fails for any reason).
        countdown: Time in seconds into the future that this Task should execute.
          Defaults to zero.
        eta: A datetime.datetime specifying the absolute time at which the task
          should be executed. Must not be specified if 'countdown' is specified.
          This may be timezone-aware or timezone-naive. If None, defaults to now.
          For pull tasks, no worker will be able to lease this task before the
          time indicated by eta.
  
      Returns:
        A taskqueue.Task instance if return_task was True. This task will *not*
        have a name, thus to ensure reliable execution of your pipeline you
        should add() this task as part of a separate Datastore transaction.
  
      Raises:
        PipelineExistsError if the pipeline with the given idempotence key exists.
        PipelineSetupError if the pipeline could not start for any other reason.
docstring_summary: Starts a new instance of this pipeline.
docstring_tokens: Starts a new instance of this pipeline .
function: def start(self,
              idempotence_key='',
              queue_name='default',
              base_path='/_ah/pipeline',
              return_task=False,
              countdown=None,
              eta=None):
      """Starts a new instance of this pipeline.
  
      Args:
        idempotence_key: The ID to use for this Pipeline and throughout its
          asynchronous workflow to ensure the operations are idempotent. If
          empty a starting key will be automatically assigned.
        queue_name: What queue this Pipeline's workflow should execute on.
        base_path: The relative URL path to where the Pipeline API is
          mounted for access by the taskqueue API or external requests.
        return_task: When True, a task to start this pipeline will be returned
          instead of submitted, allowing the caller to start off this pipeline
          as part of a separate transaction (potentially leaving this newly
          allocated pipeline's datastore entities in place if that separate
          transaction fails for any reason).
        countdown: Time in seconds into the future that this Task should execute.
          Defaults to zero.
        eta: A datetime.datetime specifying the absolute time at which the task
          should be executed. Must not be specified if 'countdown' is specified.
          This may be timezone-aware or timezone-naive. If None, defaults to now.
          For pull tasks, no worker will be able to lease this task before the
          time indicated by eta.
  
      Returns:
        A taskqueue.Task instance if return_task was True. This task will *not*
        have a name, thus to ensure reliable execution of your pipeline you
        should add() this task as part of a separate Datastore transaction.
  
      Raises:
        PipelineExistsError if the pipeline with the given idempotence key exists.
        PipelineSetupError if the pipeline could not start for any other reason.
      """
      if not idempotence_key:
        idempotence_key = uuid.uuid4().hex
      elif not isinstance(idempotence_key, unicode):
        try:
          idempotence_key.encode('utf-8')
        except UnicodeDecodeError:
          idempotence_key = hashlib.sha1(idempotence_key).hexdigest()
  
      pipeline_key = db.Key.from_path(_PipelineRecord.kind(), idempotence_key)
      context = _PipelineContext('', queue_name, base_path)
      future = PipelineFuture(self.output_names, force_strict=True)
      try:
        self._set_values_internal(
            context, pipeline_key, pipeline_key, future, _PipelineRecord.WAITING)
        return context.start(
            self, return_task=return_task, countdown=countdown, eta=eta)
      except Error:
        # Pass through exceptions that originate in this module.
        raise
      except Exception, e:
        # Re-type any exceptions that were raised in dependent methods.
        raise PipelineSetupError('Error starting %s#%s: %s' % (
            self, idempotence_key, str(e)))
function_tokens: def start ( self , idempotence_key = '' , queue_name = 'default' , base_path = '/_ah/pipeline' , return_task = False , countdown = None , eta = None ) : if not idempotence_key : idempotence_key = uuid . uuid4 ( ) . hex elif not isinstance ( idempotence_key , unicode ) : try : idempotence_key . encode ( 'utf-8' ) except UnicodeDecodeError : idempotence_key = hashlib . sha1 ( idempotence_key ) . hexdigest ( ) pipeline_key = db . Key . from_path ( _PipelineRecord . kind ( ) , idempotence_key ) context = _PipelineContext ( '' , queue_name , base_path ) future = PipelineFuture ( self . output_names , force_strict = True ) try : self . _set_values_internal ( context , pipeline_key , pipeline_key , future , _PipelineRecord . WAITING ) return context . start ( self , return_task = return_task , countdown = countdown , eta = eta ) except Error : # Pass through exceptions that originate in this module. raise except Exception , e : # Re-type any exceptions that were raised in dependent methods. raise PipelineSetupError ( 'Error starting %s#%s: %s' % ( self , idempotence_key , str ( e ) ) )