def _add_data_attribute(self, data_attr):
        """Add a data attribute to the datastream structure.

        Data attributes require processing before they can be interpreted as
        datastream. This function grants that it is adding the attribute to
        the correct datastream or creating a new datastream if necessary.
        """
        attr_name = data_attr.header.attr_name

        stream = self._find_datastream(attr_name)
        if stream is None:
            stream = Datastream(attr_name)
            self.data_streams.append(stream)
        stream.add_data_attribute(data_attr)
Add a data attribute to the datastream structure.

        Data attributes require processing before they can be interpreted as
        datastream. This function grants that it is adding the attribute to
        the correct datastream or creating a new datastream if necessary.