Why isalnum() didn't output False when I use punctuations, spaces, etc in input?

[ardavegok]

def main():
    plate = input("Plate: ")
    if is_valid(plate):
        print("Valid")
    else:
        print("Invalid")

#Much like a list, a str is a “sequence” (of characters), which means it can be “sliced” into shorter strings with syntax like s[i:j]. For instance, if s is "CS50", then s[0:2] would be "CS".
#str.isalnum() eturn True if all characters in the string are alphanumeric and there is at least one character, False otherwise.  
# Alfanümerik, A ile Z arasındaki harfler ile 0 – 9 arasındaki rakamları kapsayan karakter topluluğudur
def is_valid(s):
    n=0
    if 2<=len(s)<=6:
        for k in s:
            if k.isalnum():
                for i in s[0:2]:
                    if i.isnumeric():
                        return False
                for j in s:
                    if n==0 and j=="0":
                       return False
                    else:
                        if j.isnumeric():
                            n=1
                            
                        elif n==1 and j.isnumeric()==False:
                            return False
            
            else: 
                return False
            return True
    else:
        return False
    
main()

deanhystad write Jun-14-2024, 08:43 PM:
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