class_docstr: Transform square matrices to nearest SPD matrices
class_docstr_tok: ["Transform","square","matrices","to","nearest","SPD","matrices"]
code: def fit(self, X, y=None):
      return self
  
file_path: pyRiemann/examples/motor-imagery/helpers/coherence_helpers.py
imports: from pyriemann.utils.base import nearest_sym_pos_def
  from sklearn.model_selection import StratifiedKFold
  from sklearn.base import clone
  from sklearn.preprocessing import LabelEncoder
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.metrics import balanced_accuracy_score
  from sklearn.ensemble import StackingClassifier
label_desc: Use image node_id 2 for calling the NearestSPD obj's underlying member method code with example usage: obj.fit(X, y) and returns: self