code: def computePredictionAccuracy(pac, pic):
    
    pcols = float(pac + pic)
    if pcols == 0:
      return 0.0
    else:
      return (pac / pcols)
docs: Given a temporal memory instance return the prediction accuracy. The accuracy
    is computed as 1 - (#correctly predicted cols / # predicted cols). The
    accuracy is 0 if there were no predicted columns.