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

Ex Input:
Sentence: 'a zebra standing by a pile of large rocks'. Replace the letter 'i' with 'x' in the sentence.

Ex Output:
a zebra standxng by a pxle of large rocks

Ex Input:
Sentence: 'the child is throwing the frisbee through the hoop'. Replace the letter 't' with 'm' in the sentence.

Ex Output:
mhe child is mhrowing mhe frisbee mhrough mhe hoop

Ex Input:
Sentence: 'a blue stop sign located near two pots of flowers'. Replace the letter 'd' with 'n' in the sentence.

Ex Output:
a blue stop sign locaten near two pots of flowers