'Online learning. Prevents rebuilding of CFTree from scratch.
Parameters
X : {array-like, sparse matrix}, shape (n_samples, n_features), None
Input data. If X is not provided, only the global clustering
step is done.'

def partial_fit(self, X=None, y=None):

    (self.partial_fit_, self.fit_) = (True, False)
    if (X is None):
        self._global_clustering()
        return self
    else:
        self._check_fit(X)
        return self._fit(X)
