code: def _scale(x, lb, ub):
      """Scales the values to be normalized to [lb, ub]."""
      return (x - lb) / (ub - lb)
  
imports: from typing import Callable, Tuple
  import tensorflow.compat.v2
  import tf_quant_finance
  from tf_quant_finance import types
  from tf_quant_finance import utils
  from tf_quant_finance.math import make_val_and_grad_fn
  from tf_quant_finance.math import optimizer
  from tf_quant_finance.models.heston import approximations
label_desc: Use image node_id 3 for calling a global function with example usage: _scale(x, lb, ub) and returns: unknown