Show the `xs` (inputs) and `ys` (targets).

def show_xys(self, xs, ys)->None:
        "Show the `xs` (inputs) and `ys` (targets)."
        from IPython.display import display, HTML
        items,names = [], xs[0].names + ['target']
        for i, (x,y) in enumerate(zip(xs,ys)):
            res = []
            cats = x.cats if len(x.cats.size()) > 0 else []
            conts = x.conts if len(x.conts.size()) > 0 else []
            for c, n in zip(cats, x.names[:len(cats)]):
                res.append(x.classes[n][c])
            res += [f'{c:.4f}' for c in conts] + [y]
            items.append(res)
        items = np.array(items)
        df = pd.DataFrame({n:items[:,i] for i,n in enumerate(names)}, columns=names)
        with pd.option_context('display.max_colwidth', -1):
            display(HTML(df.to_html(index=False)))