def negative_glob_match(glob, string):
    """Negative Glob Match Helper Function

    Returns the matching wildcard ("*") value of a glob. For example
    given the glob "*-airspeed.txt" and the filename (string)
    "swallow-airspeed.txt" will return "swallow". 

    Arguments
    ---------
    glob : string
        A glob.
    string : string
        A string the glob matched.

    Returns
    -------
    string
        The wildcard ("*") portion of the string the glob matched.

    """
    match = string
    for s in glob.split("*"):
        match = match.replace(s, "")
    return match