You can iterate through the string, replacing each vowel with an asterisk. Remember to consider both uppercase and lowercase vowels.
def replace_vowels(s):
vowels = 'aeiouAEIOU'
return ''.join('*' if char in vowels else char for char in s)
input_string = input("Enter a string: ")
output_string = replace_vowels(input_string)
print(output_string)
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