docstr: Calculate the Nth Percentile value over the time series.
  
  :param int n: Integer value of the percentile to calculate.
  :param default: Value to return as a default should the calculation not be possible.
  :return: Float representing the Nth percentile value or `None`.
docstr_tok: ["Calculate","the","Nth","Percentile","value","over","the","time","series",".",":","param","int","n",":","Integer","value","of","the","percentile","to","calculate",".",":","param","default",":","Value","to","return","as","a","default","should","the","calculation","not","be","possible",".",":","return",":","Float","representing","the","Nth","percentile","value","or","`","None","`","."]
code: def percentile(self, n, default=None):
      """
      Calculate the Nth Percentile value over the time series.
  
      :param int n: Integer value of the percentile to calculate.
      :param default: Value to return as a default should the calculation not be possible.
      :return: Float representing the Nth percentile value or `None`.
      """
      return (
          numpy.percentile(self.values, n).item()
          if self.values
          else default
      )
  
imports: import numpy
label_desc: Use image node_id 37 for calling the TimeSeries obj's underlying member method code with example usage: obj.percentile(n, default) and returns: unknown