code: def NB_calc(TP, FP, POP, w):
      """
      Calculate Net Benefit (NB).
  
      :param TP: true positive
      :type TP: int
      :param FP: false positive
      :type FP: int
      :param POP: population or total number of samples
      :type POP: int
      :param w: weight
      :type w: float
      :return: NB as float
      """
      try:
          NB = (TP - w * FP) / POP
          return NB
      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 2 for calling a global function with example usage: NB_calc(TP, FP, POP, w) and returns: NB, str