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

Example Input: Sentence: 'an older red airplane is going straight up'. Replace the letter 'h' with 'z' in the sentence.
Example Output: an older red airplane is going straigzt up

Example Input: Sentence: 'a pair of planes in an airport lot parked for boarding and exiting'. Replace the letter 'e' with 'o' in the sentence.
Example Output: a pair of planos in an airport lot parkod for boarding and oxiting

Example Input: Sentence: 'five sheep graze in a field of grass'. Replace the letter 'v' with 's' in the sentence.
Example Output:
fise sheep graze in a field of grass