That syntax makes sense. See this.
You could do, equivalently:
rpc_connection = AuthServiceProxy('http://@127.0.0.1:8332')
E.g.,
rpc_connection = AuthServiceProxy('http://__cookie__:02a4a6120f20bbf2630b39bf28e30683f4a6325c6831c9819ff64d2c5a466582@127.0.0.1:8332')
The 64 hex digits after the ‘:’ is the “password” (cookie contents).