def METHOD_NAME(self, X, y=None):
    """Placeholder for fit. Subclasses should implement this method!
    Fit the model with X.
    Parameters
    ----------
    X : array-like of shape (n_samples, n_features)
        Training data, where `n_samples` is the number of samples and
        `n_features` is the number of features.
    Returns
    -------
    self : object
        Returns the instance itself.
    """