TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a city street with cars and busses near buildings'. Replace the letter 'e' with 'd' in the sentence.

SOLUTION: a city strddt with cars and bussds ndar buildings

PROBLEM: Sentence: 'a small bird perched on some thin branches'. Replace the letter 'a' with 'f' in the sentence.

SOLUTION: f smfll bird perched on some thin brfnches

PROBLEM: Sentence: 'the computer is being operated by an infant'. Replace the letter 'f' with 'o' in the sentence.

SOLUTION:
the computer is being operated by an inoant