code: def check_X_y(X, y):
      
      if len(X) != len(y):
          raise ValueError('Inconsistent input and output data shapes. '\
                           'found X: {} and y: {}'.format(X.shape, y.shape))
docs: tool to ensure input and output data have the same number of samples
  
      Parameters
      ----------
      X : array-like
      y : array-like
  
      Returns
      -------
      None