TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a couple giraffes walking through a fielded area'. Replace the letter 'e' with 'c' in the sentence.

SOLUTION: a couplc giraffcs walking through a ficldcd arca

PROBLEM: Sentence: 'a dog with his tongue out riding on a skateboard'. Replace the letter 's' with 'b' in the sentence.

SOLUTION: a dog with hib tongue out riding on a bkateboard

PROBLEM: Sentence: 'two trains traveling past each other on train tracks'. Replace the letter 'h' with 'y' in the sentence.

SOLUTION:
two trains traveling past eacy otyer on train tracks