Broken Keyboard

Given what is supposed to be typed and what is actually typed, write a function that returns the broken key(s). The function looks like:

findBrokenKeys(correct phrase, what you actually typed)

Examples

findBrokenKeys("happy birthday", "hawwy birthday") ➞ ["p"]

findBrokenKeys("starry night", "starrq light") ➞ ["y", "n"]

findBrokenKeys("beethoven", "affthoif5") ➞ ["b", "e", "v", "n"]

Notes

• Broken keys should be ordered by when they first appear in the sentence.
• Only one broken key per letter should be listed.
• Letters will all be in lower case.