Method __init__

Construct a DPM-Solver. We support both DPM-Solver (`algorithm_type="dpmsolver"`) and DPM-Solver++ (`algorithm_type="dpmsolver++"`). We also support the "dynamic thresholding" method in Imagen[1]. For pixel-space diffusion models, you can set both `algorithm_type="dpmsolver+

(
        self,
        model_fn,
        noise_schedule,
        algorithm_type="dpmsolver++",
        correcting_x0_fn=None,
        correcting_xt_fn=None,
        thresholding_max_val=1.,
        dynamic_thresholding_ratio=0.995,
        img = None,
    )