TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a fire hydrant with a message painted on it'. Replace the letter 'n' with 'j' in the sentence.

SOLUTION: a fire hydrajt with a message paijted oj it

PROBLEM: Sentence: 'a herd of zebra grazing in a lush green field'. Replace the letter 'h' with 'j' in the sentence.

SOLUTION: a jerd of zebra grazing in a lusj green field

PROBLEM: Sentence: 'a donut that has been partially eaten sitting on a napkin'. Replace the letter 'a' with 'g' in the sentence.

SOLUTION:
g donut thgt hgs been pgrtiglly egten sitting on g ngpkin