Comments line containing `what` in string `data`.

    Args:
        data (str): Configuration file in string.
        what (str): Line which will be commented out.

    Returns:
        str: Configuration file with commented `what`.

def comment(data, what):
    """
    Comments line containing `what` in string `data`.

    Args:
        data (str): Configuration file in string.
        what (str): Line which will be commented out.

    Returns:
        str: Configuration file with commented `what`.
    """
    data = data.splitlines()

    data = map(
        lambda x: "#" + x if x.strip().split() == what.split() else x,
        data
    )

    return "\n".join(data)