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

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: 'a man rolling dough in the kitchen'. Replace the letter 'a' with 'e' in the sentence.
Example Output: e men rolling dough in the kitchen

Example Input: Sentence: 'a couple of trains traveling along train tracks'. Replace the letter 'a' with 'g' in the sentence.
Example Output:
g couple of trgins trgveling glong trgin trgcks