Return a GAF 2.0-compatible string representation of the annotation.

        Parameters
        ----------

        Returns
        -------
        str
            The formatted string.

def get_gaf_format(self):
        """Return a GAF 2.0-compatible string representation of the annotation.

        Parameters
        ----------

        Returns
        -------
        str
            The formatted string.
        """
        sep = '\t'
        return sep.join(
            [self.gene, self.db_ref, self.term.id, self.evidence,
             '|'.join(self.db_ref), '|'.join(self.with_)])