Determining difference from vowels, consonants, or neither using nested-if's

Question

I am trying to figure out how to, using only nested-if, determine whether the character that was inputted is a vowel, consonant, or neither.

The problem I have is that I can't find a way to insert "neither' into the code, since nested-if uses only if or else.

Sadly, I can't use anything fancy to solve it, only simple coding. I'd prefer some explanations or examples rather than typing out the solution.

def main ():
    print ('This program determines whether a character is a vowel, a consonant, or neither.')
    print ()

    char = input('Enter a character: ')

    checker (char)

def checker (char):
    if char == 'a':
        print (char, 'is a vowel.')
        if char == 'e':
            print (char, 'is a vowel.')
        else:
            if char == 'i':
                print (char, 'is a vowel.')
            else:
                if char == 'o':
                    print (char, 'is a vowel.')
                else:
                    if char == 'u':
                        print (char, 'is a vowel.')
                    else:
                            print (char, 'is a consonant.')


print (char, 'is neither a vowel nor a consonant.')


main ()