How to use the zstandard.frame_content_size function in zstandard

def test_empty(self):
        cctx = zstd.ZstdCompressor()
        frame = cctx.compress(b"")

        self.assertEqual(zstd.frame_content_size(frame), 0)

def test_bad_frame(self):
        with self.assertRaisesRegex(
            zstd.ZstdError, "error when determining content size"
        ):
            zstd.frame_content_size(b"invalid frame header")

def test_unknown(self):
        cctx = zstd.ZstdCompressor(write_content_size=False)
        frame = cctx.compress(b"foobar")

        self.assertEqual(zstd.frame_content_size(frame), -1)

def test_empty(self):
        with self.assertRaisesRegex(
            zstd.ZstdError, "error when determining content size"
        ):
            zstd.frame_content_size(b"")

def test_too_small(self):
        with self.assertRaisesRegex(
            zstd.ZstdError, "error when determining content size"
        ):
            zstd.frame_content_size(b"foob")

def test_basic(self):
        cctx = zstd.ZstdCompressor()
        frame = cctx.compress(b"foobar")

        self.assertEqual(zstd.frame_content_size(frame), 6)