In this task, you need to replace a letter in the sentence with another given letter.

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

Example Input: Sentence: 'busy city street with pedestrians and cars with lights all around'. Replace the letter 'r' with 'k' in the sentence.
Example Output: busy city stkeet with pedestkians and caks with lights all akound

Example Input: Sentence: 'a young man holding a cell phone over a crowd'. Replace the letter 'o' with 'n' in the sentence.
Example Output:
a ynung man hnlding a cell phnne nver a crnwd