def _has_converged(centroids, old_centroids):
    """
    Stop if centroids stop to update
    Parameters
    -----------
    centroids: array-like, shape=(K, n_samples)     
    old_centroids: array-like, shape=(K, n_samples)
    ------------    
    returns
    True: bool
    
    """
    return (set([tuple(a) for a in centroids]) == set([tuple(a) for a in old_centroids]))
Stop if centroids stop to update
    Parameters
    -----------
    centroids: array-like, shape=(K, n_samples)     
    old_centroids: array-like, shape=(K, n_samples)
    ------------    
    returns
    True: bool