text: 
  class DummyTracer(object):
      def __init__(self, with_subtracer=False):
          super(DummyTracer, self).__init__()
          if with_subtracer:
              self._tracer = object()
          self.spans = []
  
      def clear(self):
          self.spans = []
  
      def start_span(self, operation_name, child_of=None):
          span = DummySpan(operation_name, child_of=child_of)
          self.spans.append(span)
          return span
  
  class DummySpan(object):
      def __init__(self, operation_name='span', child_of=None):
          super(DummySpan, self).__init__()
          self.operation_name = operation_name
          self.child_of = child_of
          self.tags = {}
          self.is_finished = False
  
      def set_tag(self, name, value):
          self.tags[name] = value
  
      def finish(self):
          self.is_finished = True
  
  