code: def _condense(self, data):
      '''
      Condense by adding together all of the lists.
      '''
      rval = {}
      for resolution,histogram in data.items():
        for value,count in histogram.items():
          rval[ value ] = count + rval.get(value,0)
      return rvaf _condense(self, data):
      '''
      Condense by adding together all of the lists.
      '''
      rval = {}
      for resolution,histogram in data.items():
        for value,count in histogram.items():
          rval[ value ] = count + rval.get(value,0)
      return rval
docs: Condense by adding together all of the lists.