TypeError: get_names() takes 0 positional arguments but 1 was given

[Truman]

module...:

#! python 3
#  I wonder who the five most popular mathematicians are?

from requests import get
from requests.exceptions import RequestException
from contextlib import closing
from bs4 import BeautifulSoup


def simple_get(url):
    """
    Attempts to get the content at `url` by making an HTTP GET request.
    If the content-type of response is some kind of HTML/XML, return the
    text content, otherwise return None.
    """
    try:
        with closing(get(url, stream=True)) as resp:
            if is_good_response(resp):
                return resp.content
            else:
                return None

    except RequestException as e:
        log_error('Error during requests to {0} : {1}'.format(url, str(e)))
        return None


def is_good_response(resp):
    """
    Returns True if the response seems to be HTML, False otherwise.
    """
    content_type = resp.headers['Content-Type'].lower()
    return (resp.status_code == 200 
            and content_type is not None 
            and content_type.find('html') > -1)


def log_error(e):
    """
    It is always a good idea to log errors. 
    This function just prints them, but you can
    make it do anything.
    """
    print(e)

def get_names():
    """
    Downloads the page where the list of mathematicians is found
    and returns a list of strings, one per mathematician
    """
    url = 'http://www.fabpedigree.com/james/mathmen.htm'
    response = simple_get(url)

    if response is not None:
        html = BeautifulSoup(response, 'html.parser')
        names = set()       # set ensures that you don’t end up with duplicate names.
        for li in html.select('li'):
            for name in li.text.split('\n'):
                if len(name) > 0:
                    names.add(name.strip())
        return list(names)
	# Raise an exception if we failed to get any data from the url
    raise Exception(f'Error retrieving contents at {format(url)}')

...used to run program...:

from bs4 import BeautifulSoup
from mathematicians import get_names

raw_html = get_names('http://www.fabpedigree.com/james/mathmen.htm')
html = BeautifulSoup(raw_html, 'html.parser')
for i, li in enumerate(html.select('li')):
	print(i, li.text)

...but error appears:

Error:
Traceback (most recent call last):
  File "C:\Python37\kodovi\mathlist1.py", line 4, in <module>
    raw_html = get_names('http://www.fabpedigree.com/james/mathmen.htm')
TypeError: get_names() takes 0 positional arguments but 1 was given

I tried to add an argument in module in definition of function get_names() but then other error appears.
Don't know how to improve the code to start the program. The desired outcome is a list where one string is per one mathematicians.