Randomize letters and digits in a Leo (http://leoeditor.com/) subtree, best installed as a @button node.

gistfile1.py

# WARNING - no undo
# randomize letters and digits in a subtree to allow sensitive
# information to be used in examples of Leo usage (http://leoeditor.com/)

from random import sample
from string import lowercase, uppercase, digits

def blur(s):
    s = [sample(lowercase, 1)[0] if i in lowercase else
         sample(uppercase, 1)[0] if i in uppercase else
         sample(digits, 1)[0]  if i in digits else i for i in s]
    return ''.join(s)

for nd in p.self_and_subtree():
    nd.h = blur(nd.h)
    nd.b = blur(nd.b)

c.redraw()