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

Example Input: Sentence: 'a dog wearing a hat on top of it's head'. Replace the letter 'g' with 'o' in the sentence.
Example Output: a doo wearino a hat on top of it's head

Example Input: Sentence: 'a young boy in a shopping cart looking at tooth brushes'. Replace the letter 'o' with 'r' in the sentence.
Example Output: a yrung bry in a shrpping cart lrrking at trrth brushes

Example Input: Sentence: 'a zebra stands in the wild surrounded by plants and trees'. Replace the letter 't' with 'a' in the sentence.
Example Output:
a zebra saands in ahe wild surrounded by planas and arees