code: def percentile(sorted_list, percent, key=lambda x: x):
      
      if not sorted_list:
          return None
      if percent == 1:
          return float(sorted_list[-1])
      if percent == 0:
          return float(sorted_list[0])
      n = len(sorted_list)
      i = percent * n
      if ceil(i) == i:
          i = int(i)
          return (sorted_list[i-1] + sorted_list[i]) / 2
      return float(sorted_list[ceil(i)-1])
docs: Find the percentile of a sorted list of values.
  
      Arguments
      ---------
      sorted_list : list
          A sorted (ascending) list of values.
      percent : float
          A float value from 0.0 to 1.0.
      key : function, optional
          An optional function to compute a value from each element of N.
  
      Returns
      -------
      float
          The desired percentile of the value list.
  
      Examples
      --------
      >>> sorted_list = [4,6,8,9,11]
      >>> percentile(sorted_list, 0.4)
      7.0
      >>> percentile(sorted_list, 0.44)
      8.0
      >>> percentile(sorted_list, 0.6)
      8.5
      >>> percentile(sorted_list, 0.99)
      11.0
      >>> percentile(sorted_list, 1)
      11.0
      >>> percentile(sorted_list, 0)
      4.0