TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'one wall in the room is flanked by a lovely piece of furniture which displays several object d'art'. Replace the letter 'n' with 'z' in the sentence.

SOLUTION: oze wall iz the room is flazked by a lovely piece of furziture which displays several object d'art

PROBLEM: Sentence: 'the cargo train is headed to the next destination'. Replace the letter 'h' with 'x' in the sentence.

SOLUTION: txe cargo train is xeaded to txe next destination

PROBLEM: Sentence: 'a bathroom with a sink and a mirror'. Replace the letter 'a' with 'x' in the sentence.

SOLUTION:
x bxthroom with x sink xnd x mirror