text: import json
  
  
  class TimeLiner:
      _timeline_dict = None
  
      def update_timeline(self, chrome_trace):
          # convert crome trace to python dict
          chrome_trace_dict = json.loads(chrome_trace)
          # for first run store full trace
          if self._timeline_dict is None:
              self._timeline_dict = chrome_trace_dict
          # for other - update only time consumption, not definitions
          else:
              for event in chrome_trace_dict['traceEvents']:
                  # events time consumption started with 'ts' prefix
                  if 'ts' in event:
                      self._timeline_dict['traceEvents'].append(event)
  
      def save(self, f_name):
          with open(f_name, 'w') as f:
              json.dump(self._timeline_dict, f)