code: def get_variable(self, variable_reference):
          '''
          :raises KeyError
          '''
          frames_tracker = self._get_tracker_for_variable_reference(variable_reference)
          if frames_tracker is None:
              raise KeyError()
          return frames_tracker.get_variable(variable_referencef get_variable(self, variable_reference):
          '''
          :raises KeyError
          '''
          frames_tracker = self._get_tracker_for_variable_reference(variable_reference)
          if frames_tracker is None:
              raise KeyError()
          return frames_tracker.get_variable(variable_reference)
docs: :raises KeyError