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

Example Input: Sentence: 'a baseball player running to third base from second'. Replace the letter 'a' with 'u' in the sentence.
Example Output: u busebull pluyer running to third buse from second

Example Input: Sentence: 'a photo of a river with a train bridge across it'. Replace the letter 'r' with 'f' in the sentence.
Example Output: a photo of a fivef with a tfain bfidge acfoss it

Example Input: Sentence: 'a bedroom with a bed, sink and a window'. Replace the letter 'd' with 'v' in the sentence.
Example Output:
a bevroom with a bev, sink anv a winvow