title: Keras: 'Sequential' object has no attribute '_feed_input_names'
body: <p>I try to create a multi-label classificator using Keras. The training data has the following format:</p>
  
  <p><strong>X_train</strong></p>
  
  <pre><code>f1  f2  f3
  1   1   5
  0   2   4
  1   0   4
  </code></pre>
  
  <p><strong>y_train:</strong></p>
  
  <pre><code>c1  c2
  0   1
  1   1
  0   0
  </code></pre>
  
  <p>This is the code that I use to build the model:</p>
  
  <pre><code>from keras.models import Sequential
  from keras.layers import Dense
  import math
  
  def softmax(z):
      z_exp = [math.exp(i) for i in z]
      sum_z_exp = sum(z_exp)
      return [i / sum_z_exp for i in z_exp]
  
  nn = Sequential()
  nn.add(Dense(10, activation="relu", input_shape=(10,)))
  nn.add(Dense(2, activation="sigmoid"))
  
  nn.compile(optimizer='adam', loss='binary_crossentropy', metrics=['accuracy'])
  
  n = 10000
  model.fit(X_train.values, y_train.values, batch_size=16, epochs=5, verbose=1, validation_split=0.1)
  </code></pre>
  
  <p>When I run this code, it fails with the message:</p>
  
  <blockquote>
    <p>AttributeError: 'Sequential' object has no attribute '_feed_input_names'</p>
  </blockquote>