import re


def extract_issue(string):
    """Extracts the issue number from the information extracted from Zoobank

    Args:
        string (str): String being passed by the Item Pipeline

    Returns:
        str: String with the available issue
    """
    # This regex will get issue numbers, even if its separated by '-', en-dash,
    # or '/'.
    # Issues numbers are always presented in between parenteses, right after the
    # volume number
    issue = re.search('(?<=\()[0-9]+[\/|\-|\–]?[0-9]*(?=\))', string)

    # Thus, if there are the parentheses and a regex match, return it, otherwise
    # return an empty string
    if '(' in string and ')' in string and issue != None:
        return issue.group()
    else:
        return ''