import re
strings = [
    "race a car",
    "A man, a plan, a canal: Panama"
]

for s in strings:
    s = re.sub(r"[^a-zA-Z0-9]+", "", "".join(s).lower())
    if s == s[::-1]:
        print("true: for {0}".format(s))
    else:
        print("false: for {0}".format(s))