title: Retrieve OPC UA Space address using python library
body: <p>I am trying to obtain my address space from my opc ua server.
  I tried using opcua-asyncio, using the simple-client.py script:</p>
  
  <pre><code>import asyncio
  import sys
  sys.path.insert(0, "..")
  import logging
  from asyncua import Client, Node, ua
  
  logging.basicConfig(level=logging.INFO)
  _logger = logging.getLogger('asyncua')
  
  
  async def main():
      url = 'opc.tcp://serveraddress/Server'
      # url = 'opc.tcp://commsvr.com:port/UA/CAS_UA_Server'
      async with Client(url=url) as client:
          # Client has a few methods to get proxy to UA nodes that should always be in address space such as Root or Objects
          root = client.get_root_node()
          _logger.info('Objects node is: %r', root)
  
          # Node objects have methods to read and write node attributes as well as browse or populate address space
          _logger.info('Children of root are: %r', await root.get_children())
  
          uri = "http://opcfoundation.org/UA/"
          idx = await client.get_namespace_index(uri)
          print(idx)
          # get a specific node knowing its node id
          var = client.get_node(ua.NodeId(85, 0))
          #var = client.get_node('i=85')
          #var = await root.get_child("[0: Objects , 0:Types , 0:Views]")
          print("My variable", var, await var.read_value())
          # print(var)
          # var.get_data_value() # get value of node as a DataValue object
          # var.read_value() # get value of node as a python builtin
          # var.write_value(ua.Variant([23], ua.VariantType.Int64)) #set node value using explicit data type
          # var.write_value(3.9) # set node value using implicit data type
  
  if __name__ == '__main__':
      loop = asyncio.get_event_loop()
      loop.set_debug(True)
      loop.run_until_complete(main())
      loop.close()
  </code></pre>
  
  <p>but every time I try to use it I get the same error:</p>
  
  <blockquote>
    <p>File ".\client.py", line 39, in 
    asyncua.ua.uaerrors._auto.BadAttributeIdInvalid: The attribute is
    not supported for the specified Node.(BadAttributeIdInvalid)</p>
  </blockquote>
  
  <p>Does anyone knows how to solve it? 
  Thank you so much</p>