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

Example Input: Sentence: 'a batter is batting at a baseball game'. Replace the letter 'b' with 'e' in the sentence.
Example Output: a eatter is eatting at a easeeall game

Example Input: Sentence: 'a book shelf full of books and nick nacks '. Replace the letter 'o' with 'm' in the sentence.
Example Output: a bmmk shelf full mf bmmks and nick nacks 

Example Input: Sentence: 'a crowd of people standing at a social get together'. Replace the letter 'a' with 'p' in the sentence.
Example Output:
p crowd of people stpnding pt p socipl get together