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

Example Input: Sentence: 'a red stop signed has been altered to say stop hate'. Replace the letter 'e' with 't' in the sentence.
Example Output: a rtd stop signtd has bttn alttrtd to say stop hatt

Example Input: Sentence: 'a train traveling through a dark tunnel next to green brush.'. Replace the letter 'r' with 'e' in the sentence.
Example Output: a teain teaveling theough a daek tunnel next to geeen beush.

Example Input: Sentence: 'a plate topped with a bacon and broccoli salad'. Replace the letter 'o' with 't' in the sentence.
Example Output:
a plate ttpped with a bactn and brtcctli salad