docstr: Test square loss for momentum optimizer.
docstr_tok: ["Test","square","loss","for","momentum","optimizer","."]
code: def test_square_momentum(self):
      """Test square loss for momentum optimizer."""
      model_vars, loss = self._test_loss_opt("square", "momentum")
  
imports: import math
  import unittest
  import jax.numpy
  import numpy
  import objax
  from objax.variable import TrainVar, VarCollection
label_desc: Use image node_id 13 for calling the TestOptimizers obj's underlying member method code with example usage: obj.test_square_momentum() without return types