In this task, you need to replace a letter in the sentence with another given letter.

Example Input: Sentence: 'a woman sitting on a bench under a gazebo'. Replace the letter 's' with 'u' in the sentence.
Example Output: a woman uitting on a bench under a gazebo

Example Input: Sentence: 'a broken suitcase on a small tile floor with the contents exposed'. Replace the letter 'u' with 'z' in the sentence.
Example Output: a broken szitcase on a small tile floor with the contents exposed

Example Input: Sentence: 'a road sign signaling that france is around the corner'. Replace the letter 'a' with 'm' in the sentence.
Example Output:
m romd sign signmling thmt frmnce is mround the corner