In Python 3:

a = (None, False, 0, 1)
assert next(filter(None, a)) == 1

In Python 2.6:

a = (None, False, 0, 1)
assert next(iter(filter(None, a))) == 1

In Python 3:

a = (None, False, 0, 1)
assert next(filter(None, a)) == 1

In Python 2.6:

a = (None, False, 0, 1)
assert next(iter(filter(None, a))) == 1

EDIT: I thought it was obvious, but apparently not: instead of None you can pass a function (or a lambda) with a check for the condition:

a = [2,3,4,5,6,7,8]
assert next(filter(lambda x: x%2, a)) == 3