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

Example Input: Sentence: 'a family opens gifts in a room with their dog, while sitting on couches'. Replace the letter 's' with 'l' in the sentence.
Example Output: a family openl giftl in a room with their dog, while litting on couchel

Example Input: Sentence: 'there is a piece of a cake on the plate and a cup of drink'. Replace the letter 'r' with 'u' in the sentence.
Example Output: theue is a piece of a cake on the plate and a cup of duink

Example Input: Sentence: 'a person wearing a helmet and goggles taking a picture with their snowboard'. Replace the letter 'r' with 'y' in the sentence.
Example Output:
a peyson weaying a helmet and goggles taking a pictuye with theiy snowboayd