Draw bounding box on `ax`.

def _draw_rect(ax:plt.Axes, b:Collection[int], color:str='white', text=None, text_size=14):
    "Draw bounding box on `ax`."
    patch = ax.add_patch(patches.Rectangle(b[:2], *b[-2:], fill=False, edgecolor=color, lw=2))
    _draw_outline(patch, 4)
    if text is not None:
        patch = ax.text(*b[:2], text, verticalalignment='top', color=color, fontsize=text_size, weight='bold')
        _draw_outline(patch,1)