human
I wrote the below code

    f = PlainTextFormatter()
    def set_fp(p):
        f.float_precision = p
    nt.assert_raises(ValueError, set_fp, '%')
    nt.assert_raises(ValueError, set_fp, '%.3f%i')
    nt.assert_raises(ValueError, set_fp, 'foo')
    nt.assert_raises(ValueError, set_fp, (-1))

What's a good function header?
assistant
#Here's a good function header.

def test_bad_precision():