text: import json
  
  from pyrsistent import thaw
  from pyrsistent import v
  
  from task_processing.interfaces.event import Event
  from task_processing.interfaces.event import json_deserializer
  from task_processing.interfaces.event import json_serializer
  from task_processing.interfaces.persistence import Persister
  
  
  class FilePersistence(Persister):
      def __init__(self, output_file):
          self.output_file = output_file
  
      def read(self, task_id):
          acc = v()
          with open(self.output_file, 'r') as f:
              for line in f:
                  parsed = json.loads(line, object_hook=json_deserializer)
                  if parsed['task_id'] == task_id:
                      acc = acc.append(Event.create(parsed))
          return acc
  
      def write(self, event):
          with open(self.output_file, 'a+') as f:
              f.write("{}\n".format(json.dumps(
                  thaw(event), default=json_serializer)))
  