code: def percent_k(data, period):
      
      catch_errors.check_for_period_error(data, period)
      percent_k = [((data[idx] - np.min(data[idx+1-period:idx+1])) /
           (np.max(data[idx+1-period:idx+1]) -
            np.min(data[idx+1-period:idx+1]))) for idx in range(period-1, len(data))]
      percent_k = fill_for_noncomputable_vals(data, percent_k)
  
      return percent_k
docs: %K.
  
      Formula:
      %k = data(t) - low(n) / (high(n) - low(n))