print the mirror image of string in Python3

Question

I'm trying to develop function mirror() that takes a string and returns its mirror image but only if the mirror image can be represented using letter in the alphabet.

>>>mirror('vow')
'wov'
>>>mirror('bed')
'INVALID'

My code doesn't give me correct answers. Thanks for any tips!

def mirror(word):
    a={'b':'d','d':'b', 'i':'i', 'o':'o','v':'v','w':'w','x':'x'}
    res=''

    for letter in word:
        if letter in a:
            res=res+a[letter]
            return res

        else:
            return 'INVALID'

    return res

Answer 1

The return res in the if statement needs to be removed, the program currently exits if the first letter is a match and returns that.

Answer 2

This should work

    def mirror(word):
    a={'b':'d','d':'b', 'i':'i', 'o':'o','v':'v','w':'w','x':'x'}
    res=''

    for letter in word:
        if letter in a:
            res += a[letter]


        else:
            return 'INVALID'

    return res

print(mirror("bob"))

return will break out of your function so once it finds the first letter it will stop running.

I also changed

res=res+a[letter]

to....

res += a[letter]