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

Example Input: Sentence: 'a single person is working in the cluttered kitchen'. Replace the letter 'n' with 'e' in the sentence.
Example Output: a siegle persoe is workieg ie the cluttered kitchee

Example Input: Sentence: 'a box of a dozen doughnuts all varieties'. Replace the letter 'l' with 'i' in the sentence.
Example Output: a box of a dozen doughnuts aii varieties

Example Input: Sentence: 'a line of several teddy bears waits on a shelf labeled "travel necessities."'. Replace the letter 'e' with 't' in the sentence.
Example Output:
a lint of stvtral ttddy btars waits on a shtlf labtltd "travtl ntctssitits."