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

Example Input: Sentence: 'a man standing in the water flying a kite'. Replace the letter 'w' with 's' in the sentence.
Example Output: a man standing in the sater flying a kite

Example Input: Sentence: 'a couple walking down a sidewalk next to some graffiti'. Replace the letter 'a' with 'y' in the sentence.
Example Output: y couple wylking down y sidewylk next to some gryffiti

Example Input: Sentence: 'a red park ride bus at a curb with a green/white bus behind'. Replace the letter 'h' with 'x' in the sentence.
Example Output:
a red park ride bus at a curb witx a green/wxite bus bexind