lowest substring of a containing all characters of string b

sublength.py

def sublength(a, b):
	hash_b = {}
	for char in set(b):
		hash_b[char] = -1
	min_length = len(a)+1
	for i, char in enumerate(a):
		if char in hash_b:
			hash_b[char] = i
		if (min(hash_b.values()) != -1) & (i - min(hash_b.values()) + 1 < min_length) :
			print hash_b
			min_length = i - min(hash_b.values()) + 1
	if min_length != len(a) + 1:
		return min_length
	else:
		return 0

print sublength("asdfgdghgo","sdfh")