code: def fit(self, X, y):
      K = rbf_kernel(X, gamma=self.gamma)
      self.X_train_ = X
      super().fit(K, y)
      return self
  
file_path: lightning/examples/plot_sparse_non_linear.py
imports: import numpy
  import pylab
  from sklearn.metrics.pairwise import rbf_kernel
  from lightning.classification import CDClassifier
  from lightning.classification import KernelSVC
label_desc: Use image node_id 2 for calling the SparseNonlinearClassifier obj's underlying member method code with example usage: obj.fit(X, y) and returns: self