class_docstr: Unnormalized rational quadratic kernel
  
  .. math::
      k(|x-y|) = (1+|x-y|^2/(2 \alpha \ell^2))^{-\alpha}
  
  where :math:`\ell` is the `lengthscale` (autodetected or given).
code: def __init__(self, lengthscale=None, alpha=1.0):
      super().__init__()
      self.alpha = alpha
      self.lengthscale = lengthscale
  
imports: from typing import Optional
  import torch
  from .None import Detector
  import torchdrift.utils
label_desc: Use image node_id 1 to create a new RationalQuadraticKernel object from inherited base classes: Kernel with example: obj = RationalQuadraticKernel(lengthscale, alpha)