Returns the coordination geometry of the given IUPAC symbol.
        :param IUPAC_symbol: The IUPAC symbol of the coordination geometry.

def get_geometry_from_IUPAC_symbol(self, IUPAC_symbol):
        """
        Returns the coordination geometry of the given IUPAC symbol.
        :param IUPAC_symbol: The IUPAC symbol of the coordination geometry.
        """
        for gg in self.cg_list:
            if gg.IUPAC_symbol == IUPAC_symbol:
                return gg
        raise LookupError(
            'No coordination geometry found with IUPAC symbol "{symbol}"'.format(
                symbol=IUPAC_symbol))