title: UnetSocket send() returns a Nonetype object
body: <p>I am trying out the python code specified in the UnetStack Handbook. While running <strong>tx.py</strong> and <strong>rx.py</strong>, UnetSocket object is created successfully as I print it out on the terminal, but the send() function sends Nonetype data at the receiver.</p>
  <p><strong>tx.py</strong> ===&gt;&gt;</p>
  <pre><code>from unetpy import UnetSocket
  
  s = UnetSocket('localhost',1101)
  print(s)
  s.send('hellooo',31)
  s.close()
  </code></pre>
  <hr />
  <p><strong>rx.py</strong> =====&gt;&gt;&gt;</p>
  <pre><code>from unetpy import UnetSocket
  s = UnetSocket('localhost',1102)
  rx = s.receive()
  print('here ',rx)
  print('from node : ',bytearray(rx.data).decode())
  s.close()
  </code></pre>
  <p>First I run 2-node-network.groovy on the Simulator.
  Then rx.py and next tx.py from the terminal.</p>
  <p><strong>Error at rx.py</strong>
  Traceback (most recent call last):
  File &quot;rx.py&quot;, line 6, in </p>
  <pre><code>print('from node : ',bytearray(rx.data).decode())
  
  AttributeError: 'NoneType' object has no attribute 'data'
  </code></pre>
  <p><strong>O/p at tx.py</strong>
  &lt;unetpy.UnetSocket object at 0x7fe2909d4550&gt;</p>