# Question: Write a Python program to check whether a given character is a vowel or consonant.

def main(char: str) -> None:
    vowels = 'aeiou'
    if char.lower() in vowels:
        print(f"{char} is a vowel.")
    elif char.isalpha():
        print(f"{char} is a consonant.")
    else:
        raise ValueError("Invalid input. Please enter an alphabetic character.")
        

if __name__ == '__main__':
    main('a')
    main('b')
    main('A')
    main('1') # also works with a int