replace vowels

[niru]

hello, i have a list with some names, and i have to replace wovels by " - "
here is what i tried:

list1 = ['john', 'tony', 'luck]


def replace_vowel(mlist):
            vowels = "aeiouy"
            novowel = ""
            for char in mlist:
                if char in vowels:
                    novowel = novowel.replace(char, '-')
                    return mlist

print replace_vowel(list1)

actually , the output is " None "
It has to be:

Output:
['j-hn', 't-n-', 'l-ck']

any idea? thanks !