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

Example Input: Sentence: 'a open entrance leading to a set of closed doors'. Replace the letter 'd' with 'f' in the sentence.
Example Output: a open entrance leafing to a set of closef foors

Example Input: Sentence: 'a bathroom that has  a sink and a toilet'. Replace the letter 's' with 'a' in the sentence.
Example Output: a bathroom that haa  a aink and a toilet

Example Input: Sentence: 'a crowd of young children sitting down at a white table sharing a meal'. Replace the letter 'l' with 'y' in the sentence.
Example Output:
a crowd of young chiydren sitting down at a white tabye sharing a meay