CTCI 1.4 Palindrome Permutation

from collections import Counter
import string as ss


def check_pal_per(string):
    string = string.lower()
    hashset = set()

    for s in string:
        if s == " ":
            continue
        elif s not in hashset:
            hashset.add(s)
        else:
            hashset.remove(s)

    if len(hashset) == 0:
        return True
    elif len(hashset) % 2 !=0 and len(hashset) == 1:
        return True

    else:
        return False

def clean(string):
    return [c for c in string.lower() if c in ss.ascii_lowercase]

def check_pal_per_counter(string):
    counter = Counter(clean(string))
    return sum(c%2 for c in counter.values()) <= 1

test_cases = [
        ("aba", True),
        ("aab", True),
        ("abba", True),
        ("aabb", True),
        ("a-bba", True),
        ("a-bba!", True),
        ("Tact Coa", True),
        ("jhsabckuj ahjsbckj", True),
        ("Able was I ere I saw Elba", True),
        ("So patient a nurse to nurse a patient so", False),
        ("Random Words", False),
        ("Not a Palindrome", False),
        ("no x in nixon", True),
        ("azAZ", True),
    ]
func = [
    check_pal_per,
    check_pal_per_counter
]

Test Function

def runtest(func, test_cases):
    for fun in func:
        print(fun.__name__)
        print("---------------")
        for val, result in test_cases:
            o = fun(val)
            if o == result:
                print("Passed ✓ for '%s'"%val)
            else:
                print("X Error for val '{}', expected: {}, got: {}".format(val, result,  check_pal_per(val)))
    print()