code: def mirror(K):
      """Mirrors an upper triangular kernel matrix, helper for Sqize_kernel."""
      return K - np.diag(np.diag(K)) + np.transpose(K)
  
imports: import collections
  from functools import partial
  import numpy
  from scipy.sparse.linalg import svds
  from sklearn.base import BaseEstimator, TransformerMixin
  from sktime.dists_kernels.base import BasePairwiseTransformerPanel
label_desc: Use image node_id 16 for calling a global function with example usage: mirror(K) and returns: unknown