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

Example Input: Sentence: 'you are never to old to play with the nintendo wii'. Replace the letter 'e' with 'v' in the sentence.
Example Output: you arv nvvvr to old to play with thv nintvndo wii

Example Input: Sentence: 'a brown door  that says gentlemen and a toilet'. Replace the letter 'o' with 'f' in the sentence.
Example Output: a brfwn dffr  that says gentlemen and a tfilet

Example Input: Sentence: 'two tennis players are approaching the net for an argument'. Replace the letter 'r' with 'f' in the sentence.
Example Output:
two tennis playefs afe appfoaching the net fof an afgument