def get_mentions(status_dict, exclude=[]):
    """
    Given a status dictionary, return all people mentioned in the toot,
    excluding those in the list passed in exclude.
    """
    # Canonicalise the exclusion dictionary by lowercasing all names and
    # removing leading @'s
    for i, user in enumerate(exclude):
        user = user.casefold()
        if user[0] == "@":
            user = user[1:]

        exclude[i] = user

    users = [user["username"] for user in status_dict["mentions"]
             if user["username"].casefold() not in exclude]
    return users