def test_countparens_empty():
assert 0 == parens.count_parens("")
def test_countparens_countsOpens():
assert 1 == parens.count_parens("(")
assert 2 == parens.count_parens("((")
def test_countparens_subtractsCloseds():
assert -1 == parens.count_parens(")")
assert -2 == parens.count_parens("))")
assert -1 == parens.count_parens("())")
assert 0 == parens.count_parens("()")