def get_range(coordinates, axis, buffer):
    """
    Based on lat/lon of the underlying data, get a range which defines the
    bounding box for the map

    Parameters
    ----------
    coordinates: xarray DataArray
        Coordinate data of the underlying data
    axis: str
        axis of the data (lat/lon) by which to slice the coordinates DataArray
    buffer: float
        value, expressed as a fraction of the range of the underlying data,
        to add as a buffer to the bounding box

    Returns
    -------
    list, defining the range as input_range +/- input_range * buffer
    """
    _range = [
        coordinates.loc[dict(coordinates=axis)].min().item(),
        coordinates.loc[dict(coordinates=axis)].max().item(),
    ]
    _offset = abs(_range[1] - _range[0]) * 0.1
    return [_range[0] - _offset, _range[1] + _offset]