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

SOLUTION: a cfowd stands undef a set of lights in the ceiling and one pefson holds up a cell phone

PROBLEM: Sentence: 'a shower, toilet and sink are highlights in this clean bathroom'. Replace the letter 'e' with 'd' in the sentence.

SOLUTION: a showdr, toildt and sink ard highlights in this cldan bathroom

PROBLEM: Sentence: 'a small gold and black clock tower in a village'. Replace the letter 'c' with 'e' in the sentence.

SOLUTION:
a small gold and blaek eloek tower in a village