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

Example Input: Sentence: 'a skater looks ahead as he rides down a ramp'. Replace the letter 'n' with 'm' in the sentence.
Example Output: a skater looks ahead as he rides dowm a ramp

Example Input: Sentence: 'a woman walks by with a large suitcase and a polka dot umbrella'. Replace the letter 'e' with 'n' in the sentence.
Example Output: a woman walks by with a largn suitcasn and a polka dot umbrnlla

Example Input: Sentence: 'a dog is sticking his head out the window of a moving car'. Replace the letter 'h' with 'w' in the sentence.
Example Output:
a dog is sticking wis wead out twe window of a moving car