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

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: 'there is a young baby that is wearing a tie'. Replace the letter 't' with 'c' in the sentence.
Example Output: chere is a young baby chac is wearing a cie

Example Input: Sentence: 'a girl is smiling while holding a dog'. Replace the letter 'h' with 'v' in the sentence.
Example Output:
a girl is smiling wvile volding a dog