code: def part_sum(start, end):
      """Calculates partial sum"""
      sum = 0
      for x in range(start, end):
          if x % 2 == 0:
              sum -= 1.0 / x
          else:
              sum += 1.0 / x
      return sum
  
imports: import math
  import sys
  import time
  import ppft
label_desc: Use image node_id 1 for calling a global function with example usage: part_sum(start, end) and returns: sum