title: Input multiple datasets to tensorflow model
body: <p>Hi I'm trying to input multiple datasets in a model. This is an example of my problem, however in my case one of my models has 2 input parameters while the other one has one. The error I get in my case is :</p>
  <pre><code>Failed to find data adapter that can handle input: (&lt;class 'list'&gt; containing values of types {&quot;&lt;class 'tensorflow.python.data.ops.dataset_ops.BatchDataset'&gt;&quot;, &quot;&lt;class 'tensorflow.python.data.ops.dataset_ops.TakeDataset'&gt;&quot;}), &lt;class 'NoneType'&gt;
  </code></pre>
  <p>Code:</p>
  <pre><code>import tensorflow as tf
  
  # Create first model
  model1 = tf.keras.Sequential()
  model1.add(tf.keras.layers.Dense(1))
  model1.compile()
  model1.build([None,3])
  
  # Create second model
  model2 = tf.keras.Sequential()
  model2.add(tf.keras.layers.Dense(1))
  model2.compile()
  model2.build([None,3])
  
  
  # Concatenate
  fusion_model = tf.keras.layers.Concatenate()([model1.output, model2.output])
  t = tf.keras.layers.Dense(1, activation='tanh')(fusion_model)
  model = tf.keras.models.Model(inputs=[model1.input, model2.input], outputs=t)
  model.compile()
  
  #Datasets
  ds1 = tf.data.Dataset.from_tensors(([1,2,3],1))
  ds2 = tf.data.Dataset.from_tensors(([1,2,3], 2))
  
  print(ds1)
  print(ds2)
  # Fit
  model.fit([ds1,ds2])
  </code></pre>
  <p>Running this example code produces that:</p>
  <pre><code>Failed to find data adapter that can handle input: (&lt;class 'list'&gt; containing values of types {&quot;&lt;class 'tensorflow.python.data.ops.dataset_ops.TensorDataset'&gt;&quot;}), &lt;class 'NoneType'&gt;
  </code></pre>
  <p>I need to use the dataset modules because they provide in built lazy loading of the data.</p>