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

Example Input: Sentence: 'an old rusty car sits outside of an old building'. Replace the letter 'o' with 'r' in the sentence.
Example Output: an rld rusty car sits rutside rf an rld building

Example Input: Sentence: 'nine geese flying south for the winter months'. Replace the letter 't' with 'f' in the sentence.
Example Output: nine geese flying soufh for fhe winfer monfhs

Example Input: Sentence: 'a brown teddy bear wrapped in black wiring'. Replace the letter 'l' with 'j' in the sentence.
Example Output:
a brown teddy bear wrapped in bjack wiring