Doing a "cast" from Unicode strings to look-alike ASCII characters

scrub.py

# coding=utf-8
import string

sourcemap = u"àáâãäåÀÁÂÃÄÅèéêëÈÉÊËìíîïÌÍÎÏòóôõöÒÓÔÕÖùúûüÙÚÛÜýÿÝñÑ¿¡";
destmap   =  "aaaaaaAAAAAAeeeeEEEEiiiiIIIIoooooOOOOOuuuuUUUUyyYnN?!";

def scrub(s, replacement_char=''):
	"""Returns a new string with accented characters replaced by the closest ASCII character available.
	This is conceptually similar to multiple passes with maketrans+translate."""
	scrubbed_sentence = "";
	for letter in s:
		if letter in string.ascii_letters or letter in string.digits or letter in string.punctuation or letter == ' ':
			scrubbed_sentence += str(letter);
		elif letter in sourcemap:
			scrubbed_sentence += destmap[sourcemap.index(letter)];
		else:
			scrubbed_sentence += replacement_char;
	return scrubbed_sentence;