code: def init(port=8813, numRetries=10, host="localhost", label="default"):
      
      _connections[label] = connect(port, numRetries, host)
      switch(label)
      return getVersion()
docs: Establish a connection to a TraCI-Server and store it under the given
      label. This method is not thread-safe. It accesses the connection
      pool concurrently.