TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a man with a backpack on a motorcycle'. Replace the letter 't' with 'd' in the sentence.

SOLUTION: a man widh a backpack on a modorcycle

PROBLEM: Sentence: 'a book shelf full of books and nick nacks '. Replace the letter 'o' with 'm' in the sentence.

SOLUTION: a bmmk shelf full mf bmmks and nick nacks 

PROBLEM: Sentence: 'a zebra with a swinging tail looking at the camera'. Replace the letter 's' with 'a' in the sentence.

SOLUTION:
a zebra with a awinging tail looking at the camera