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

Example Input: Sentence: 'a hipster riding a skateboard up the side of a wall'. Replace the letter 's' with 'm' in the sentence.
Example Output: a hipmter riding a mkateboard up the mide of a wall

Example Input: Sentence: 'stone and white colored structure in front of white modern building'. Replace the letter 'r' with 'p' in the sentence.
Example Output: stone and white coloped stpuctupe in fpont of white modepn building

Example Input: Sentence: 'a cell phone has a ritz cracker like keychain'. Replace the letter 'r' with 's' in the sentence.
Example Output:
a cell phone has a sitz csackes like keychain