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

Example Input: Sentence: 'a couple of giraffe standing next to each other near  a fence'. Replace the letter 'f' with 'j' in the sentence.
Example Output: a couple oj girajje standing next to each other near  a jence

Example Input: Sentence: 'a skier with his legs covered in snow lifts one of his feet to stamp it'. Replace the letter 's' with 'y' in the sentence.
Example Output: a ykier with hiy legy covered in ynow lifty one of hiy feet to ytamp it

Example Input: Sentence: 'airplanes at the airport getting ready to take off'. Replace the letter 'e' with 'h' in the sentence.
Example Output:
airplanhs at thh airport ghtting rhady to takh off