Write a program to determine if a string contains only unique characters.
Return true if it does and false otherwise.

The string may contain any of the 128 ASCII characters.
Characters are case-sensitive, e.g. 'a' and 'A' are considered different characters.

Difficulty: EASY
Starter code: def has_unique_chars(str):
	

Solutions:
def has_unique_chars(s):
	return len(s) == len(set(s))


def has_unique_chars(str):
	return len(set(str)) == len(str)


def has_unique_chars(s):
	return len(s) <= 128 and len(s) == len(set(s))


has_unique_chars = lambda s: not s[128:] and (not s[len(set(s)):])


has_unique_chars = lambda s: not s[len(set(s)):]


def has_unique_chars(str):
	return all((str.count(s) == 1 for s in str))


def has_unique_chars(string):
	hash = [False] * 128
	for c in string:
		if hash[ord(c)]:
			return False
		hash[ord(c)] = True
	return True