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

Example Input: Sentence: 'there is a stepladder situated over a toilet'. Replace the letter 'r' with 'x' in the sentence.
Example Output: thexe is a stepladdex situated ovex a toilet

Example Input: Sentence: 'two zebras are snuggling at the zoo in their display area'. Replace the letter 'e' with 'z' in the sentence.
Example Output: two zzbras arz snuggling at thz zoo in thzir display arza

Example Input: Sentence: 'a small yellow bird standing on wooden rails'. Replace the letter 's' with 'h' in the sentence.
Example Output:
a hmall yellow bird htanding on wooden railh