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

Example Input: Sentence: 'a crowd stands under a set of lights in the ceiling and one person holds up a cell phone'. Replace the letter 'r' with 'f' in the sentence.
Example Output: a cfowd stands undef a set of lights in the ceiling and one pefson holds up a cell phone

Example Input: Sentence: 'the large modern bathroom has two sinks and a large tub'. Replace the letter 't' with 'j' in the sentence.
Example Output: jhe large modern bajhroom has jwo sinks and a large jub

Example Input: Sentence: 'there is no image on this page to describe'. Replace the letter 't' with 'h' in the sentence.
Example Output:
hhere is no image on hhis page ho describe