code: def _zero_centered_scale(ar):
      ar[ar > 0] = ScoreBalancer._scale(ar[ar > 0])
      ar[ar < 0] = -ScoreBalancer._scale(-ar[ar < 0])
      return (ar + 1) / 2.0
  
imports: from abc import ABC, abstractmethod
  import numpy
  import pandas
  from scipy.stats import norm, rankdata
  from scattertext.Common import DEFAULT_SCALER_ALGO, DEFAULT_BETA
label_desc: Use image node_id 3 for calling the ScoreBalancer obj's underlying member method code with example usage: obj._zero_centered_scale(ar) and returns: unknown