code: def custom_activation_fn(self, x: tf.Tensor) -> tf.Tensor:
      return tf.keras.activations.sigmoid(x)
  
imports: from typing import Any, List, cast
  import tensorflow
  from packaging import version
  from tensorflow.keras.layers import Dense
  from tensorflow.keras.losses import binary_crossentropy
  from tensorflow.keras.metrics import categorical_accuracy
  from tensorflow.keras.models import Sequential
  from determined import keras
  from tests.experiment.tf_utils import make_xor_data_sequences
label_desc: Use image node_id 2 for calling the XORTrialWithCustomObjects obj's underlying member method code with example usage: obj.custom_activation_fn(x) and returns: tf