import re


def extract_address(input_string):
    """Extracts an IP address from a blob of text.

    Params:
    - input_string: (type: string) string to parse.

    Returns:
    - result: (type: string) extracted IP address.
    """
    if input_string:
        addr_search = re.search(
            r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}(?:/\d{1,2}|)',
            input_string)

        if bool(addr_search):
            return addr_search.group()

    return None