from typing import Optional
import re


def parse_host(link: str) -> Optional[str]:
    """
    Parse the host name in a given link
    Args:
        link: Link to a website

    Returns:
        str: the host name
    """
    pattern = re.compile("^http[s]?://([a-z0-9]*\.[a-z]*)[/]?[a-zA-z0-9]*?$")
    matches = pattern.match(link)
    if matches:
        return matches.group(1)  # it's the only possible group
    else:
        return None