import re

def get_urls(string:str = None) -> list:
    """
    Extracts URLs from a given string using regular expressions.

    Parameters:
    string (str): The input string from which URLs need to be extracted.

    Returns:
    list: A list of URLs extracted from the input string.
    """
    regex = re.compile(
        r'((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+@)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+@)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w_]*)?\??(?:[-\+=&;%@.\w_]*)#?(?:[.\!\/\\w]*))?)',
        re.IGNORECASE)

    return [x[0] for x in re.findall(regex, string)]