code: def normal_range(mean, sd, treshold=1.28):
      
      bottom = mean - sd*treshold
      top = mean + sd*treshold
      return(bottom, top)
docs: Returns a bottom and a top limit on a normal distribution portion based on a treshold.
  
      Parameters
      ----------
      treshold : float
          maximum deviation (in terms of standart deviation). Rule of thumb of a gaussian distribution: 2.58 = keeping 99%, 2.33 = keeping 98%, 1.96 = 95% and 1.28 = keeping 90%.
  
      Returns
      ----------
      (bottom, top) : tuple
          Lower and higher range.
  
      Example
      ----------
      >>> import neurokit as nk
      >>> bottom, top = nk.normal_range(mean=100, sd=15, treshold=2)
  
      Notes
      ----------
      *Authors*
  
      - `Dominique Makowski <https://dominiquemakowski.github.io/>`_