docstr: partial sum for truncated natural logarithm
docstr_tok: ["partial","sum","for","truncated","natural","logarithm"]
code: def partial_sum(self, x):
      """
      partial sum for truncated natural logarithm
      """
      return sum(
          [
              float(i % 2 and 1 or -1) * x**i / i
              for i in range(1, self.n)
          ]
      )
  
file_path: ppft/ppft/tests/auto_diff.py
imports: import math
  import sys
  import ppft
label_desc: Use image node_id 3 for calling the PartialSum obj's underlying member method code with example usage: obj.partial_sum(x) and returns: sum