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

Example Input: Sentence: 'an umbrella sitting on top of a hill next to a body of water'. Replace the letter 't' with 'b' in the sentence.
Example Output: an umbrella sibbing on bop of a hill nexb bo a body of waber

Example Input: Sentence: 'a small dog in the back compartment of a backpack'. Replace the letter 'c' with 'd' in the sentence.
Example Output: a small dog in the badk dompartment of a badkpadk

Example Input: Sentence: 'baby in a stripped shirt holding a teddy bear'. Replace the letter 'd' with 'k' in the sentence.
Example Output:
baby in a strippek shirt holking a tekky bear