python3 docopt throws usage error while using pyCharm

I need some basic help on docopt with python3.7 .I am using in pyCharm. I tried to let run the example code which is shown on the docopt.org website. But the system is throwing usage errors. I installed the doctop through pip install docopt an have version 0.6.2 . I found a thread with the same error messages, but the user didn't have a docstring in it, so that is why it didn't work for him.

Here is the code:

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""Naval fate.

Usage:
  naval_fate.py  ship new <name>...
  naval_fate.py  ship <name> move <x> <y> [ --speed=<kn>]
  naval_fate.py  ship shoot <x> <y>
  naval_fate.py  mine (set|remove) <x> <y> [--moored|--drifting}
  naval_fate.py  -h| --help
  naval_fate.py  --version

Options:
  -h --help     Show this screen.
  --version     Show version.  
  --speed=<kn>  Speed in knots [default: 10].
  -- moored     Moored (anchored) mine.
  -- drifting   Drifting mine.

"""
from docopt import docopt

if __name__ == '__main__':
    arguments = docopt(__doc__, version='1')
    print(arguments)

Here is ther ERROR:

...\Scripts\python.exe 
.../naval_fate.py
Traceback (most recent call last):
  File 
".../naval_fate.py", line 27, in <module>
    arguments = docopt(__doc__, version='1')
  File "...\lib\site-packages\docopt.py", line 558, in docopt
    DocoptExit.usage = printable_usage(doc)
  File "...\lib\site-packages\docopt.py", line 466, in printable_usage
    usage_split = re.split(r'([Uu][Ss][Aa][Gg][Ee]:)', doc)
  File "C:\Python\Python37\Lib\re.py", line 213, in split
    return _compile(pattern, flags).split(string, maxsplit)
TypeError: expected string or bytes-like object

Process finished with exit code 1

What I tried:

deleted the file extensions of naval_fate.py.
uninstalled and reinstalled docopt.
changed the positions of the words in and after the usage and options sections.
used two spaces between the options and the text (as found in another thread)
tried to format outside the docstring in diffrent ways.

e.g

from docopt
...
arguments = docopt.docopt(__doc__, version='1')

instead of

from docopt import docopt
...
arguments = docopt(__doc__, version='1')

But it all didn't help. Does anybody have an idea? Thanks so far.

Solution

Well, I found it! It was the curly braces at the end of the line in the 'Usage' part.

naval_fate.py  mine (set|remove) <x> <y> [--moored|--drifting}

After changing it to ] everything worked well.
Hopefully I can help someone else with this little(big) mistake.