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

Example Input: Sentence: 'a dog laying in front of a horses stall with the horse peeking over the half door'. Replace the letter 'a' with 'b' in the sentence.
Example Output: b dog lbying in front of b horses stbll with the horse peeking over the hblf door

Example Input: Sentence: 'a boy riding his skate board on an obstacle course'. Replace the letter 'e' with 'b' in the sentence.
Example Output: a boy riding his skatb board on an obstaclb coursb

Example Input: Sentence: 'older couple of men posing out front of city bus in street'. Replace the letter 'e' with 'w' in the sentence.
Example Output:
oldwr couplw of mwn posing out front of city bus in strwwt