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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 _normalize_timestamps(self, timestamp, intervals, config):
    '''
    Helper for the subclasses to generate a list of timestamps.
    '''
    rval = [timestamp]
    if intervals<0:
      while intervals<0:
        rval.append( config['i_calc'].normalize(timestamp, intervals) )
        intervals += 1
    elif intervals>0:
      while intervals>0:
        rval.append( config['i_calc'].normalize(timestamp, intervals) )
        intervals -= 1
    return rval