def METHOD_NAME(self):
    """Set up temperature, pressure, and relative humidity cubes that
    contain multiple height levels; in this case the values of these
    diagnostics are identical on each level."""
    super().METHOD_NAME()
    self.height_points = np.array([5.0, 10.0, 20.0])
    height_attribute = {"positive": "up"}
    data = np.array([[-88.15, -13.266943, 60.81063]], dtype=np.float32)
    self.wet_bulb_temperature = set_up_variable_cube(
        data, name="wet_bulb_temperature", units="Celsius"
    )
    self.wet_bulb_temperature = add_coordinate(
        self.wet_bulb_temperature,
        self.height_points,
        "height",
        coord_units="m",
        attributes=height_attribute,
    )