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

Example Input: Sentence: 'a couple of white street signs sitting on top of a pole'. Replace the letter 'n' with 't' in the sentence.
Example Output: a couple of white street sigts sittitg ot top of a pole

Example Input: Sentence: 'a silly cow licking the camera through a fence'. Replace the letter 't' with 'v' in the sentence.
Example Output: a silly cow licking vhe camera vhrough a fence

Example Input: Sentence: 'a cup of coffee and a donut in the box'. Replace the letter 'o' with 'j' in the sentence.
Example Output:
a cup jf cjffee and a djnut in the bjx