Ошибка при запуске сервера bokeh: "OSError: [Errno 98] Address already in use". Пример из мануала

Это пример из туториола по Bokeh.

from tornado.ioloop import IOLoop  
from bokeh.application.handlers import FunctionHandler   
from bokeh.application import Application  
from bokeh.models import ColumnDataSource  
from bokeh.plotting import figure  
from bokeh.server.server import Server  


def modify_doc(doc):

    x_values = range(10)
    y_values = [x ** 2 for x in x_values]
    data_source = ColumnDataSource(data=dict(x=x_values, y=y_values))
    plot = figure(title="f(x) = x^2",
                  tools="crosshair,pan,reset,save,wheel_zoom",)
    plot.line('x', 'y', source=data_source, line_width=3, line_alpha=0.6)
    doc.add_root(plot)
    doc.title = "Test Plot"


def main():

    print("Preparing a bokeh application.")
    io_loop = IOLoop.current()
    bokeh_app = Application(FunctionHandler(modify_doc))

    server = Server({"/": bokeh_app}, io_loop=io_loop)
    server.start()
    print("Opening Bokeh application on http://localhost:5006/")

    io_loop.add_callback(server.show, "/")
    io_loop.start()


main()

При запуске скрипт выдает:

2020-03-24 20:32:48,249 Starting Bokeh server version 2.0.0 (running on Tornado 6.0.4)  
2020-03-24 20:32:48,249 User authentication hooks NOT provided (default user enabled)  
2020-03-24 20:32:48,251 Bokeh app running at: http://localhost:5006/grbr  
2020-03-24 20:32:48,251 Starting Bokeh server with process id: 6345  
Preparing a bokeh application.  
2020-03-24 20:32:48,418 Starting Bokeh server version 2.0.0 (running on Tornado 6.0.4)  
2020-03-24 20:32:48,419 Error running application handler  <bokeh.application.handlers.script.ScriptHandler object at 0x7f4adf515390>: [Errno 98] Address already in use  
File "netutil.py", line 174, in bind_sockets:  
sock.bind(sockaddr) Traceback (most recent call last):  
File "/usr/local/lib/python3.7/dist-packages/bokeh/application/handlers/code_runner.py", line   196, in run  
    exec(self._code, module.__dict__)  
  File "/home/gluk/my_bin/bin_trash/grbr.py", line 50, in <module>  
    main()  
  File "/home/gluk/my_bin/bin_trash/grbr.py", line 42, in main  
    server = Server({"/": bokeh_app}, io_loop=io_loop)  
  File "/usr/local/lib/python3.7/dist-packages/bokeh/server/server.py", line 390, in __init__  
    sockets, self._port = bind_sockets(self.address, self.port)  
  File "/usr/local/lib/python3.7/dist-packages/bokeh/server/util.py", line 60, in bind_sockets  
    ss = netutil.bind_sockets(port=port or 0, address=address)  
  File "/usr/local/lib/python3.7/dist-packages/tornado/netutil.py", line 174, in bind_sockets  
    sock.bind(sockaddr)  
OSError: [Errno 98] Address already in use  

2020-03-24 20:32:48,615 404 GET /favicon.ico (::1) 0.47ms  
2020-03-24 20:32:48,643 WebSocket connection opened  
2020-03-24 20:32:48,643 ServerConnection created  
2020-03-24 20:33:01,625 WebSocket connection closed: code=1001, reason=None  

Не могу понять причину данной ошибки. И второй вопрос: в мануале написано, что скрипт может запускаться

$ python grbr.py  

но запускается он только:

bokeh serve --show grbr.py