TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a yellow fire truck parked in a parking lot'. Replace the letter 'a' with 'y' in the sentence.

SOLUTION: y yellow fire truck pyrked in y pyrking lot

PROBLEM: Sentence: 'people wait for a train on a snowy sidewalk'. Replace the letter 'n' with 'm' in the sentence.

SOLUTION: people wait for a traim om a smowy sidewalk

PROBLEM: Sentence: 'a skull cup sitting on top of a bathroom sink'. Replace the letter 'm' with 'y' in the sentence.

SOLUTION:
a skull cup sitting on top of a bathrooy sink