Is there a Python dict without values?

Question

Instead of this:

a = {\"foo\": None, \"bar\": None}

Is there a way to write this?

b = {\"foo\", \"bar\"}

Answer 1

In order to "key" into a set in constant time use in:

>>> s = set(['foo', 'bar', 'baz'])
>>> 'foo' in s
True
>>> 'fork' in s
False