code: def g(c, Nrot):
      """Nonlinear function mapping interactions to free energy."""
      w = tf.Variable(
          tf.random_normal(
              [
                  1,
              ],
              stddev=0.3,
          )
      )
      return c / (1 + w * Nrot)
  
imports: from __future__ import print_function
  from __future__ import division
  from __future__ import unicode_literals
  import warnings
  import numpy
  import tensorflow
  from deepchem.models import Model
  from deepchem.nn import model_ops
  import deepchem.utils.rdkit_util
label_desc: Use image node_id 13 for calling a global function with example usage: g(c, Nrot) and returns: unknown