title: Run into the following issue: build_tensor_flow is not supported in Eager Mode
body: <p>I am playing around with TensorFlow, and I am trying to export a Keras Model as a TensorFlow Model. And I ran into the above-mentioned error. I am following the "Build Deep Learning Applications with Keras 2.0" from Lynda (<a href="https://www.linkedin.com/learning/building-deep-learning-applications-with-keras-2-0/exporting-google-cloud-compatible-models?u=42751868" rel="noreferrer">https://www.linkedin.com/learning/building-deep-learning-applications-with-keras-2-0/exporting-google-cloud-compatible-models?u=42751868</a>) </p>
  
  <p>While trying to build a tensor flow model, I came across this error, thrown at line 66 where the add meta graphs and variables function is defined.</p>
  
  <p><em>line 66, in build_tensor_info
      raise RuntimeError("build_tensor_info is not supported in Eager mode.")
  RuntimeError: build_tensor_info is not supported in Eager mode.</em></p>
  
  <pre><code>...model_builder.add_meta_graph_and_variables(
          K.get_session(),
          tags=[tf.compat.v1.saved_model.tag_constants.SERVING],
          signature_def_map={
              tf.compat.v1.saved_model.signature_constants.DEFAULT_SERVING_SIGNATURE_DEF_KEY: signature_def
          }
      )
  ...
  </code></pre>
  
  <p>Any thoughts folks?</p>