code: def RACCU_calc(TOP, P, POP):
      """
      Calculate Random accuracy unbiased (RACCU).
  
      :param TOP: number of positives in predict vector
      :type TOP: int
      :param P: number of actual positives
      :type P: int
      :param POP: population or total number of samples
      :type POP: int
      :return: RACCU as float
      """
      try:
          result = ((TOP + P) / (2 * POP)) ** 2
          return result
      except (ZeroDivisionError, TypeError):
          return "None"
  
imports: from __future__ import division
  import math
  from .pycm_util import normal_quantile
  from .pycm_interpret import *
  from .pycm_param import CLASS_PARAMS
label_desc: Use image node_id 20 for calling a global function with example usage: RACCU_calc(TOP, P, POP) and returns: result, str