如何替换此代码中的元音？

def replace_vowels(string, replacement):
    vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U']
    for vowel in vowels:
        string = string.replace(vowel, replacement)
    return string

# 示例用法
code = "This is a sample code."
replacement = "*"
new_code = replace_vowels(code, replacement)
print(new_code)