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

Example Input: Sentence: 'a small child reaching back with a wii remote'. Replace the letter 'l' with 'o' in the sentence.
Example Output: a smaoo chiod reaching back with a wii remote

Example Input: Sentence: 'a man standing on a tennis court holding a tennis racquet'. Replace the letter 'c' with 'y' in the sentence.
Example Output: a man standing on a tennis yourt holding a tennis rayquet

Example Input: Sentence: 'a mother elephant and her young calf stand by a pool at the zoo'. Replace the letter 'y' with 'a' in the sentence.
Example Output:
a mother elephant and her aoung calf stand ba a pool at the zoo