recursively walk through a data set or json file 
        to get the total number of nodes

def _get_size_recursive(self, dat):
        """
        recursively walk through a data set or json file 
        to get the total number of nodes
        """
        self.total_records += 1
        #self.total_nodes += 1
        for rec in dat:
            if hasattr(rec, '__iter__') and type(rec) is not str:
                self._get_size_recursive(rec)
            else:
                self.total_nodes += 1
                self.total_length += len(str(rec))