code: def learn_inducing_locations(self):
      return None
  
imports: import unittest
  import torch
  import gpytorch
  from gpytorch.test.variational_test_case import VariationalTestCase
label_desc: Use image node_id 4 for calling the TestGridVariationalGP obj's underlying member method code with example usage: obj.learn_inducing_locations() and returns: None