def user_loc_value_to_class(axis_tag, user_loc):
    """Return the OS/2 weight or width class that is closest to the provided
    user location. For weight the user location is between 0 and 1000 and for
    width it is a percentage.

    >>> user_loc_value_to_class('wght', 310)
    310
    >>> user_loc_value_to_class('wdth', 62)
    2
    """
    if axis_tag == "wght":
        return int(user_loc)
    elif axis_tag == "wdth":
        return min(
            sorted(WIDTH_CLASS_TO_VALUE.items()),
            key=lambda item: abs(item[1] - user_loc),
        )[0]

    raise NotImplementedError