def find_up(name, path=None):
    """Search upward from the starting path (or the current directory)
    until the given file or directory is found. The given name is
    assumed to be a basename, not a path.  Returns the absolute path
    of the file or directory if found, or None otherwise.

    Args
    ----
    name : str
        Base name of the file or directory being searched for.

    path : str, optional
        Starting directory.  If not supplied, current directory is used.
    """
    if not path:
        path = os.getcwd()
    if not exists(path):
        return None
    while path:
        if exists(join(path, name)):
            return abspath(join(path, name))
        else:
            pth = path
            path = dirname(path)
            if path in pth:
                return None
    return None
dataset/ETHPy150Open OpenMDAO/OpenMDAO/openmdao/util/file_util.py/find_up/operator `==` -> `in`