bake a poem into a colourful cake

bake.py

#!/usr/bin/env python3
# bake.py - score a poem with colourized ANSI codes
# Type a poem at stdin, print the colourized poem at stdout.
# Requires at least 256-color support from the teletype.
import sys

def ansi(*codes):
    return "\x1b[" + ";".join(map(str, codes)) + "m"

def color(nib):
    # this is chosen based on the ANSI 16-color style
    # (i.e. 0x1 for red, 0x2 for green,
    #       0x4 for blue, 0x8 for brighter),
    # but using the 256-color ANSI format
    # (i.e. start at 16, add +1 for more red,
    #       +6 for more green, +36 for more blue),
    # with colors picked to land in a nice pastel region.
    color = (16 + 2 * 43
        + (nib >> 0 & 1) * 2 * 36
        + (nib >> 1 & 1) * 2 * 6
        + (nib >> 2 & 1) * 2 * 1
        + (nib >> 3 & 1) * 1 * 43
    )
    ch = chr(nib + (48 if nib < 10 else 55))
    return ansi(38, 5, color) + ch

def format_char(ch):
    high, low = divmod(ord(ch), 16)
    return color(high) + color(low)

for line in list(sys.stdin):
    chars = line.strip()
    print(" " + " ".join(chars))
    print("".join(format_char(ch) for ch in chars) + ansi(0))