human
Solve the following python programming problem given the following code:
@ pytest.fixture (scope = 'session') 
def jupyter_notebook(request, bokeh_server, log_file) : 
    "
    Starts a jupyter notebook server at the beginning of a session, and
    closes at the end of a session.

    Requires the bokeh_server fixture.

    Adds custom.js that runs all the cells on notebook opening. Cleans out
    this custom.js at the end of the test run.

    WARNING: Tramples on user's existing custom.js

    Returns the url that the jupyter notebook is running at.

    " 
    from jupyter_core import paths 
    config_dir = paths.jupyter_config_dir () 
    body = '
require(["base/js/namespace", "base/js/events"], function (IPython, events) {
    events.on("kernel_ready.Kernel", function () {
        IPython.notebook.execute_all_cells();
    });
});
' 
    custom = join (config_dir, 'custom') 
    if (not exists (custom)) : 
        os.makedirs (bokeh_server) 
customjs = join (custom, 'custom.js') 
    with open (customjs, 'w') as f : 
        f.write (body) 
def clean_up_customjs() : 
        with open (customjs, 'w') as f : 
            f.write ('') 
request.addfinalizer (clean_up_customjs) 
    notebook_port = pytest.config.option.notebook_port 
    env = os.environ.copy () 
    env ['BOKEH_RESOURCES'] = 'server' 
    notebook_dir = join (dirname (__file__), pardir, pardir) 
    cmd = ['jupyter', 'notebook'] 
    argv = ['--no-browser', ('--port=%s' % notebook_port), ('--notebook-dir=%s' % notebook_dir)] 
    jupter_notebook_url = ('http://localhost:%d' % notebook_port) 
    try : 
        proc = subprocess.Popen ((cmd + argv), env = env, stdout = log_file, stderr = log_file) 
except OSError : 
        write (('Failed to run: %s' % ' '.join ((cmd + argv)))) 
        sys.exit (1) 
else : 
        def stop_jupyter_notebook() : 
            write ('Shutting down jupyter-notebook ...') 
            proc.kill () 
request.addfinalizer (stop_jupyter_notebook) 
        def wait_until(func, timeout = 5.0, interval = 0.01) : 
            start = time.time () 
            while True : 
              ...

    
    

    Fix the buggy line: os.makedirs (bokeh_server)
assistant
#Here is Python code to fix the buggy line: os.

os.makedirs (custom)