def f2_score(self):
return self.fbeta_score(<NUM_LIT>)<EOL>
Return :math:`F_{2}`.

        The :math:`F_{2}` score emphasizes recall over precision in comparison
        to the :math:`F_{1}` score

        Cf. https://en.wikipedia.org/wiki/F1_score

        Returns
        -------
        float
            The :math:`F_{2}` of the confusion table

        Example
        -------
        >>> ct = ConfusionTable(120, 60, 20, 30)
        >>> ct.f2_score()
        0.8108108108108109