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

Example Input: Sentence: 'a person that is sitting under an umbrella'. Replace the letter 'a' with 'l' in the sentence.
Example Output: l person thlt is sitting under ln umbrelll

Example Input: Sentence: 'a baseball player is throwing a ball across the dirt field'. Replace the letter 'a' with 't' in the sentence.
Example Output: t btsebtll pltyer is throwing t btll tcross the dirt field

Example Input: Sentence: 'a large home made pizza ready to be cooked'. Replace the letter 'o' with 's' in the sentence.
Example Output:
a large hsme made pizza ready ts be cssked