TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a man is on a saddled horse with reins'. Replace the letter 's' with 'o' in the sentence.

SOLUTION: a man io on a oaddled horoe with reino

PROBLEM: Sentence: 'a couple walking down a sidewalk next to some graffiti'. Replace the letter 'a' with 'y' in the sentence.

SOLUTION: y couple wylking down y sidewylk next to some gryffiti

PROBLEM: Sentence: 'a bike and fire hydrant that are covered in snow'. Replace the letter 'd' with 'p' in the sentence.

SOLUTION:
a bike anp fire hyprant that are coverep in snow