TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'some brown black and white horses clouds and rocks'. Replace the letter 'a' with 'n' in the sentence.

SOLUTION: some brown blnck nnd white horses clouds nnd rocks

PROBLEM: Sentence: 'a suitcase is sitting on a sidewalk near trees'. Replace the letter 's' with 'd' in the sentence.

SOLUTION: a duitcade id ditting on a didewalk near treed

PROBLEM: Sentence: 'a young girl climbing out of a suitcase on the floor'. Replace the letter 'g' with 's' in the sentence.

SOLUTION:
a youns sirl climbins out of a suitcase on the floor