class_docstr: Incremental version of https://en.wikipedia.org/wiki/Kahan_summation_algorithm
code: def __iadd__(self, x):
      i = 0
      for y in self.partials:
          if abs(x) < abs(y):
              x, y = y, x
          hi = x + y
          lo = y - (hi - x)
          if lo:
              self.partials[i] = lo
              i += 1
          x = hi
      self.partials[i:] = [x]
      return self
  
file_path: vowpal_wabbit/python/tests/confidence_sequence.py
imports: from cmath import sqrt
label_desc: Use image node_id 2 for calling the incremental_f_sum obj's underlying member method code with example usage: obj.__iadd__(x) and returns: self