title: object does not support item assignment in tensor flow
body: <p>In the simple program before I am not able to do a simple task and get the following error.</p>
  
  <pre><code>import tensorflow as tf
  
  x_1= tf.constant([1, 2, 3])
  x_1= tf.reshape(x_1, shape= (1, 3))
  x_2= tf.constant([2, 3, 4])
  x_2= tf.reshape(x_2, shape= (1, 3))
  x_3= tf.constant([3, 4, 5])
  x_3= tf.reshape(x_3, shape= (1, 3))
  x= tf.concat((x_1, x_2, x_3), axis=0)
  
  for i in range(0, 3):
      x[i, :]= x[i, :]+ 1
  
  init= tf.global_variables_initializer()
  
  with tf.Session() as sess:
     y= sess.run(x)
  </code></pre>
  
  <p>And I get the following error:</p>
  
  <blockquote>
    <p>TypeError: 'Tensor' object does not support item assignment</p>
  </blockquote>