code: def _assert_submatrix(full, sub, n):
      """Check that "sub" is the matrix obtained \
      by removing the p-th col and row in "full".
  
      Used only for debugging.
  
      """
      true_sub = np.empty_like(sub)
      true_sub[:n, :n] = full[:n, :n]
      true_sub[n:, n:] = full[n + 1 :, n + 1 :]
      true_sub[:n, n:] = full[:n, n + 1 :]
      true_sub[n:, :n] = full[n + 1 :, :n]
  
      np.testing.assert_almost_equal(true_sub, sub)
  
imports: import collections.abc
  import itertools
  import operator
  import warnings
  import numpy
  import scipy.linalg
  from joblib import Memory, Parallel, delayed
  from sklearn.base import BaseEstimator
  from sklearn.covariance import empirical_covariance
  from sklearn.model_selection import check_cv
  from sklearn.utils.extmath import fast_logdet
  from .._utils import CacheMixin, logger
  from .._utils.extmath import is_spd
label_desc: Use image node_id 3 for calling a global function with example usage: _assert_submatrix(full, sub, n) without return types