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

Example Input: Sentence: 'a giraffe walking in its natural habitat on the savannah'. Replace the letter 't' with 'u' in the sentence.
Example Output: a giraffe walking in ius nauural habiuau on uhe savannah

Example Input: Sentence: 'a large clock on the top of pole in the middle of a walk way'. Replace the letter 'f' with 'h' in the sentence.
Example Output: a large clock on the top oh pole in the middle oh a walk way

Example Input: Sentence: 'a plate of sandwiches and some french fries'. Replace the letter 'i' with 'z' in the sentence.
Example Output:
a plate of sandwzches and some french frzes