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

Example Input: Sentence: 'closeup of two teddy bears in red scarves and a brown teddy bear'. Replace the letter 'i' with 'y' in the sentence.
Example Output: closeup of two teddy bears yn red scarves and a brown teddy bear

Example Input: Sentence: 'a man sitting on a luggage cart inside of an airport'. Replace the letter 't' with 'a' in the sentence.
Example Output: a man siaaing on a luggage cara inside of an airpora

Example Input: Sentence: 'a man sis on a public area while holding an umbrella'. Replace the letter 'o' with 'b' in the sentence.
Example Output:
a man sis bn a public area while hblding an umbrella