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

Example Input: Sentence: 'a child taking the paper off a box sitting on the floor'. Replace the letter 'c' with 'b' in the sentence.
Example Output: a bhild taking the paper off a box sitting on the floor

Example Input: Sentence: 'bags of seeds with a pair of black scissors sitting on them'. Replace the letter 'b' with 'y' in the sentence.
Example Output: yags of seeds with a pair of ylack scissors sitting on them

Example Input: Sentence: 'a plate with a piece of cake on top of it siting on a table'. Replace the letter 'o' with 'y' in the sentence.
Example Output:
a plate with a piece yf cake yn typ yf it siting yn a table