code: def tilt_model(params, shape):
      
      mx = params["mx"].value
      my = params["my"].value
      off = params["off"].value
      bg = np.zeros(shape, dtype=float) + off
      x = np.arange(bg.shape[0]) - bg.shape[0] // 2
      y = np.arange(bg.shape[1]) - bg.shape[1] // 2
      x = x.reshape(-1, 1)
      y = y.reshape(1, -1)
      bg += mx * x + my * y
      return bg
docs: lmfit tilt model