Letters Only

Write a function that removes any non-letters from a string, returning a well-known film title.

Examples

letters_only("R!=:~0o0./c&}9k`60=y") ➞ "Rocky"

letters_only("^,]%4B|@56a![0{2m>b1&4i4") ➞ "Bambi"

letters_only("^U)6$22>8p).") ➞ "Up"

Notes