    def test_tofile_sep(self):
        x = np.array([1.51, 2, 3.51, 4], dtype=float)
        f = open(self.filename, 'w')
        x.tofile(f, sep=',')
        f.close()
        f = open(self.filename, 'r')
        s = f.read()
        f.close()
        assert_equal(s, '1.51,2.0,3.51,4.0')
        os.unlink(self.filename)
The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.