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

Example Input: Sentence: 'two children who are standing next to a white fire hydrant'. Replace the letter 't' with 'r' in the sentence.
Example Output: rwo children who are sranding nexr ro a whire fire hydranr

Example Input: Sentence: 'bus with sheep decals in foreign language and doughnuts'. Replace the letter 'g' with 'i' in the sentence.
Example Output: bus with sheep decals in foreiin laniuaie and douihnuts

Example Input: Sentence: 'a couple of animals play in a watering hole'. Replace the letter 'f' with 'k' in the sentence.
Example Output:
a couple ok animals play in a watering hole