old_contents: import Queue
  import json
  
  
  class Result:
      def __init__(self):
          self.results = {}
  
      def add_result(self, client, url, result):
          if client not in self.results:
              self.results[client] = {}
          if url not in self.results[client]:
              self.results[client][url] = []
          self.results[client][url].append(result)
  
      def write(self, result_file):
          stream = open(result_file, 'w')
          stream.write(json.dumps(self.results))
          stream.close()
  
new_contents: import json
  
  
  class Result:
      def __init__(self):
          self.results = {}
  
      def add_result(self, client, url, result):
          if client not in self.results:
              self.results[client] = {}
          if url not in self.results[client]:
              self.results[client][url] = []
          self.results[client][url].append(result)
  
      def write(self, result_file):
          stream = open(result_file, 'w')
          stream.write(json.dumps(self.results))
          stream.close()
  
subject: Remove unused import