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

Example Input: Sentence: 'busy city street with pedestrians and cars with lights all around'. Replace the letter 'r' with 'k' in the sentence.
Example Output: busy city stkeet with pedestkians and caks with lights all akound

Example Input: Sentence: 'many people gathered on a sunny day flying kites'. Replace the letter 'e' with 'm' in the sentence.
Example Output: many pmoplm gathmrmd on a sunny day flying kitms

Example Input: Sentence: 'a bathroom counter filled with three sinks under mirrors'. Replace the letter 't' with 'y' in the sentence.
Example Output:
a bayhroom counyer filled wiyh yhree sinks under mirrors