new_contents: import tensorflow as tf
  import numpy as np
  import pytest
  import xquant as xq
  
  
  @pytest.mark.parametrize("name", ["hard_tanh"])
  def test_serialization(name):
      fn = tf.keras.activations.get(name)
      ref_fn = getattr(xq.activations, name)
      assert fn == ref_fn
      config = tf.keras.activations.serialize(fn)
      fn = tf.keras.activations.deserialize(config)
      assert fn == ref_fn
  
  
  def test_hard_tanh():
      real_values = np.random.uniform(-2, 2, (3, 3, 32))
      x = tf.keras.backend.placeholder(ndim=2)
      f = tf.keras.backend.function([x], [xq.activations.hard_tanh(x)])
      result = f([real_values])[0]
      np.testing.assert_allclose(result, np.clip(real_values, -1, 1))
  
subject: Add simple activations test (#48)