Fix typo

dtype is an argument to tf.cast

Author: hsm207

Diff for: Chapter1_Introduction/Ch1_Introduction_TFP.ipynb

@@ -1277,7 +1277,7 @@
         "            state_gradients_are_stopped=True),\n",
         "        bijector=unconstraining_bijectors))\n",
         "\n",
-        "tau_samples = tf.floor(posterior_tau * tf.cast(tf.size(count_data)), tf.float32)\n",
+        "tau_samples = tf.floor(posterior_tau * tf.cast(tf.size(count_data), dtype=tf.float32))\n",
         "\n",
         "# tau_samples, lambda_1_samples, lambda_2_samples contain\n",
         "# N samples from the corresponding posterior distribution\n",