input: Write a python function to create a neural network model for the Lunar Lander environment using TensorFlow.
  ```python
  def create_lunar_lander_model(state_dim, action_dim):
      model = tf.keras.Sequential()
      model.add(tf.keras.layers.Dense(128, input_dim=state_dim, activation='relu'))
      model.add(tf.keras.layers.Dense(64, activation='relu'))
      model.add(tf.keras.layers.Dense(action_dim))
      return model
  
  assert create_lunar_lander_model(8, 4).output_shape == (None, 4)
  assert len(create_lunar_lander_model(8, 4).layers) == 3
  assert create_lunar_lander_model(8, 4).layers[1].output_shape == (None, 64)
output: def create_lunar_lander_model(state_dim, action_dim):
      import tensorflow as tf
      model = tf.keras.Sequential()
      model.add(tf.keras.layers.Dense(128, input_dim=state_dim, activation='relu'))
      model.add(tf.keras.layers.Dense(64, activation='relu'))
      model.add(tf.keras.layers.Dense(action_dim))
      return model