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

Example Input: Sentence: 'a baby is holding and eating a banana'. Replace the letter 'i' with 'g' in the sentence.
Example Output: a baby gs holdgng and eatgng a banana

Example Input: Sentence: 'a person jumping up in the air on a snowboard'. Replace the letter 'r' with 'o' in the sentence.
Example Output: a peoson jumping up in the aio on a snowboaod

Example Input: Sentence: 'a young cub cuddles with one of its parents'. Replace the letter 'u' with 'f' in the sentence.
Example Output:
a yofng cfb cfddles with one of its parents