Private method for testing text data types.

def _is_numeric_data(self, data_type):
        """Private method for testing text data types."""
        dt = DATA_TYPES[data_type]
        if dt['min'] and dt['max']:
            if type(self.data) is dt['type'] and dt['min'] < self.data < dt['max']:
                self.type = data_type.upper()
                self.len = len(str(self.data))
                return True