This adds the __cause__, __context__ and __suppress_context__
members to exception objects and makes e.g., `raise exc from cause`
set them in the same way as standard Python.
This needs thorough testing before it's merged, as we tried
and reverted this once before (#5341 and #5356).
I think that besides checking for tinyusb having "something to do",
the fact that `port_interrupt_after_ticks` and `port_disable_tick`
weren't implemented that was causing a secondary problem.
I've tested this on a pico w over reboot-cycles and ctrl-c-cycles,
with and without drive automounting, with and without serial repl open,
and on a power-only connection.
I didn't notice the problem reported in #5356 after merely implementing
port_idle_until_interrupt; but I did notice that sleeps in general would
take over-long until "something" (like writing to the USB drive) happened;
I think "something" was probably calling port_enable_tick(). When this
problem was happening, sleeps would take a lot longer; for instance,
`sleep(.001)` would take about 1/20s and `sleep(.1)` would take about 1/7s.
.. a fast helper for animations. It is similar to and inspired by the
PixelMap helper in Adafruit LED Animation library, but with an extremely
fast 'paste' method for setting a series of pixels. This is a common
operation for many animations, and can give a substantial speed improvement.
It's named `adafruit_pixelmap` so that we can package a compatible version
in pure Python for systems that can't fit it in C in flash, or for
Blinka.
This is a proof of concept and can make a very fast comet animation:
```python
import time
import adafruit_pixelbuf
import adafruti_pixelmap
import board
import neopixel
from supervisor import ticks_ms
from adafruit_led_animation.animation.solid import Solid
from adafruit_led_animation import color
pixel_pin = board.GP0
pixel_num = 96
pixels = neopixel.NeoPixel(pixel_pin, pixel_num, brightness=1, auto_write=False, pixel_order="RGB")
evens = adafruit_pixelmap.PixelMap(pixels, tuple(range(0, pixel_num, 2)))
odd_indices = tuple((i, i+2) for i in range(1, pixel_num, 4))
print(odd_indices)
odds = adafruit_pixelbuf.PixelMap(pixels, odd_indices)
assert len(odds) == len(odd_indices)
comet_length = 16
comet1 = [color.calculate_intensity(color.GREEN, ((1+i) / comet_length) ** 2.4)
for i in range(comet_length)]
comet2 = [color.calculate_intensity(color.PURPLE, ((1+i) / comet_length) ** 2.4)
for i in range(comet_length)]
pos1 = 0
pos2 = 96//4
while True:
evens.paste(comet1, pos1, wrap=True, reverse=False, others=0)
pos1 = (pos1 + 1) % len(evens)
odds.paste(comet2, pos2, wrap=True, reverse=True, others=0)
pos2 = (pos2 - 1) % len(odds)
pixels.show()
m = ticks_ms()
if m % 2000 > 1000:
time.sleep(.02)
```
