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

Example Input: Sentence: 'a man is posing in a desert, leaning on a sign with an image of a camel on it'. Replace the letter 'i' with 'r' in the sentence.
Example Output: a man rs posrng rn a desert, leanrng on a srgn wrth an rmage of a camel on rt

Example Input: Sentence: 'a man eats while holding himself up in a one-hand push up position'. Replace the letter 'i' with 'p' in the sentence.
Example Output: a man eats whple holdpng hpmself up pn a one-hand push up posptpon

Example Input: Sentence: 'a crowd watching a professional tennis player serve'. Replace the letter 'o' with 'l' in the sentence.
Example Output:
a crlwd watching a prlfessilnal tennis player serve