code: def FagerMcGowan_calc(TP, FP, FN, TN):
      """
      Calculate Fager & McGowan similarity.
  
      :param TP: true positive
      :type TP: int
      :param TN: true negative
      :type TN: int
      :param FP: false positive
      :type FP: int
      :param FN: false negative
      :type FN: int
      :return: Fager & McGowan similarity as float
      """
      try:
          part1 = math.sqrt((TP + FP) * (TP + FN))
          part2 = math.sqrt(max((TP + FP), (TP + FN)))
          return (TP / part1) - (1 / (2 * part2))
      except Exception:
          return "None"
  
imports: from __future__ import division
  from enum import Enum
  import math
label_desc: Use image node_id 36 for calling a global function with example usage: FagerMcGowan_calc(TP, FP, FN, TN) and returns: unknown, str