Given a letter and an array of words, return whether the letter does not appear in any of the words.

Examples

forbidden_letter("r", ["rock", "paper", "scissors"]) ➞ false

forbidden_letter("a", ["spoon", "fork", "knife"]) ➞ true

forbidden_letter("m", []) ➞ true

Notes

• All inputs given will be in lowercase.
• You will always be given a forbidden letter, but there may be empty arrays.