def get_cn(self, structure, n, use_weights=False):
        """
        Get coordination number, CN, of site with index n in structure.

        Args:
            structure (Structure): input structure.
            n (integer): index of site for which to determine CN.
            use_weights (boolean): flag indicating whether (True)
                to use weights for computing the coordination number
                or not (False, default: each coordinated site has equal
                weight).
        Returns:
            cn (integer or float): coordination number.
        """

        siw = self.get_nn_info(structure, n)
        return sum([e['weight'] for e in siw]) if use_weights else len(siw)