code: def lift_calc(PPV, PRE):
      """
      Calculate Lift score.
  
      :param PPV: Positive predictive value (PPV)
      :type PPV: float
      :param PRE: Prevalence
      :type PRE: float
      :return: lift score as float
      """
      try:
          return PPV / PRE
      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 31 for calling a global function with example usage: lift_calc(PPV, PRE) and returns: unknown, str