better?
    def test_fisher_alpha(self):
        """fisher alpha should match hand-calculated value."""
        c = array([4,3,4,0,1,0,2])
        obs = fisher_alpha(c)
        self.assertFloatEqual(obs, 2.7823795367398798)

        # should depend only on S and N (number of species, number of individuals / seqs).
        c = array([1,6,1,0,1,0,5])
        obs = fisher_alpha(c)
        self.assertFloatEqual(obs, 2.7823795367398798)

        # should match another by hand:
        # 2 species, 62 seqs, alpha is 0.39509
        c = array([61,0,0,1])
        obs = fisher_alpha(c)
        self.assertFloatEqualAbs(obs, 0.39509, eps=.0001)