code: def LR_SE_calc(item1, item2, item3, item4):
      """
      Calculate likelihood ratio +/- standard error.
  
      :param item1: true positive or false negative (TP or FN)
      :type item1: int
      :param item2: number of actual positives (P)
      :type item2: int
      :param item3: false positive or true negative (FP or TN)
      :type item3: int
      :param item4: number of actual negatives (N)
      :type item4: int
      :return: standard error as float
      """
      try:
          return math.sqrt(
              (1 / item1) - (1 / item2) + (1 / item3) - (1 / item4)
          )
      except Exception:
          return "None"
  
file_path: pycm/pycm/pycm_ci.py
imports: from __future__ import division
  import math
label_desc: Use image node_id 4 for calling a global function with example usage: LR_SE_calc(item1, item2, item3, item4) and returns: math, str