code: def standard_deviation(data, period):
      
      catch_errors.check_for_period_error(data, period)
  
      stds = [np.std(data[idx+1-period:idx+1], ddof=1) for idx in range(period-1, len(data))]
  
      stds = fill_for_noncomputable_vals(data, stds)
      return stds
docs: Standard Deviation.
  
      Formula:
      std = sqrt(avg(abs(x - avg(x))^2))