docs: def percentile(values, percent):
      """
      PERCENTILE WITH INTERPOLATION
      RETURN VALUE AT, OR ABOVE, percentile OF THE VALUES
  
      snagged from http://code.activestate.com/recipes/511478-finding-the-percentile-of-the-values/
      """
      N = sorted(values)
      if not N:
          return None
      k = (len(N) - 1) * percent
      f = int(math.floor(k))
      c = int(math.ceil(k))
      if f == c:
          return N[int(k)]
      d0 = N[f] * (c - k)
      d1 = N[c] * (k - f)
      return d0 + d1