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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

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 rval