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

Example Input: Sentence: 'a group of people hanging around holding umbrellas'. Replace the letter 'p' with 'f' in the sentence.
Example Output: a grouf of feofle hanging around holding umbrellas

Example Input: Sentence: 'a man is standing with this luggage next to a railroad track'. Replace the letter 'g' with 'l' in the sentence.
Example Output: a man is standinl with this lullale next to a railroad track

Example Input: Sentence: 'a boy in red shirt and shorts on a skateboard'. Replace the letter 'a' with 'h' in the sentence.
Example Output:
h boy in red shirt hnd shorts on h skhtebohrd