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

Example Input: Sentence: 'a person on a snowboard does an air trick'. Replace the letter 'n' with 'o' in the sentence.
Example Output: a persoo oo a soowboard does ao air trick

Example Input: Sentence: 'a police officer on a horse is riding down the street'. Replace the letter 'h' with 'a' in the sentence.
Example Output: a police officer on a aorse is riding down tae street

Example Input: Sentence: 'a hipster taking a selfie in a bathroom mirror'. Replace the letter 'a' with 'p' in the sentence.
Example Output:
p hipster tpking p selfie in p bpthroom mirror