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

Example Input: Sentence: 'a woman walks by with a large suitcase and a polka dot umbrella'. Replace the letter 'e' with 'n' in the sentence.
Example Output: a woman walks by with a largn suitcasn and a polka dot umbrnlla

Example Input: Sentence: 'a group of men sitting at a desk with lap top computers'. Replace the letter 'p' with 'z' in the sentence.
Example Output: a grouz of men sitting at a desk with laz toz comzuters

Example Input: Sentence: 'two sheep standing next to each other in a doorway'. Replace the letter 'h' with 'd' in the sentence.
Example Output:
two sdeep standing next to eacd otder in a doorway