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

Example Input: Sentence: 'the two boys are eating large carrots while sitting on a blanket'. Replace the letter 'a' with 'q' in the sentence.
Example Output: the two boys qre eqting lqrge cqrrots while sitting on q blqnket

Example Input: Sentence: 'a memorial with various plaques and american flags on it'. Replace the letter 'a' with 'k' in the sentence.
Example Output: k memorikl with vkrious plkques knd kmerickn flkgs on it

Example Input: Sentence: 'a kitten sitting in a high top sneaker'. Replace the letter 'a' with 'f' in the sentence.
Example Output:
f kitten sitting in f high top snefker