title: python socket protocol not support
body: <p>I useed python-can-isotp on RaspberryPi3, and test it with example code, but I got an error.</p>
  
  <p>My simple code:</p>
  
  <pre><code>import isotp
  
  s = isotp.socket()
  s2 = isotp.socket()
  # Configuring the sockets.
  s.set_fc_opts(stmin=5, bs=10)
  #s.set_general_opts(...)
  #s.set_ll_opts(...)
  
  s.bind("vcan0" rxid=0x123 txid=0x456)  # We love named parameters!
  s2.bind("vcan0", rxid=0x456, txid=0x123)
  s2.send(b"Hello, this is a long payload sent in small chunks of 8 bytes.")
  print(s.recv())
  </code></pre>
  
  <p>ERROR:</p>
  
  <p><code>File "/usr/local/opt/python-3.7.0/lib/python3.7/socket.py", line 151, in __init__
      _socket.socket.__init__(self, family, type, proto, fileno)
  OSError: [Errno 93] Protocol not supported
  </code></p>
  
  <p>Can someone please help me find the solution to the problem?</p>