Write a function called get_numerals that returns a list of numbers from a string

Write a function called get_numerals. get_numerals should
accept one parameter, a string. It should return a string
containing only the numerals from the original string:
no letters, punctuation marks, or spaces.

Remember, numerals have ordinal numbers between 48 ("0")
and 57 ("9"). You may use the ord() function to get
a letter’s ordinal number.

Your function should be able to handle strings with no
numerals (return an empty string) and strings with all
numerals (return the original string). You may assume
we’ll only use regular characters (no emojis, formatting
characters, etc.).

Write your function here!

def get_numerals(a_string):
    for char in a_string:
        if ord(char) >= 48 or ord(char) <= 57:
            a_string = a_string.replace(char, "")
    return a_string

Below are some lines of code that will test your function.
You can change the value of the variable(s) to test your
function with different inputs.

If your function works correctly, this will originally
print:
1301

8675309

print(get_numerals("CS1301"))
print(get_numerals("Georgia Institute of Technology"))
print(get_numerals("8675309"))

I have tried this multiple ways and the result is that my function only returns empty strings. I know I am missing something simple. Any help is appreciated.

>Solution :

Every number is >= 48 or <= 57. You want to remove chars with ord < 48 or > 57:

def get_numerals(a_string):
    for char in a_string:
        if ord(char) < 48 or ord(char) > 57:
            a_string = a_string.replace(char, "")
    return a_string