class_docstr: Gaussian Smoothing 2D.
  
  :param sigma: sigma of the Gaussian.
  :param channels: number of channels in the output.
  :param kernel_size: aperture size.
code: def __init__(self, sigma, channels, kernel_size=None):
      kernel = _generate_gaussian_kernel(sigma, channels, kernel_size)
      super(GaussianSmoothing2D, self).__init__(kernel)
  
imports: import math
  import torch
  import torch.nn
  import torch.nn.functional
  from torch.nn.modules.utils import _quadruple
  from .base import Processor
label_desc: Use image node_id 1 to create a new GaussianSmoothing2D object from inherited base classes: ConvSmoothing2D with example: obj = GaussianSmoothing2D(sigma, channels, kernel_size)