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

Example Input: Sentence: 'a herd of zebra grazing in a lush green field'. Replace the letter 'h' with 'j' in the sentence.
Example Output: a jerd of zebra grazing in a lusj green field

Example Input: Sentence: 'a person holding on to a black remote'. Replace the letter 'n' with 'h' in the sentence.
Example Output: a persoh holdihg oh to a black remote

Example Input: Sentence: 'a small car is sandwiched between two large buses'. Replace the letter 'a' with 'm' in the sentence.
Example Output:
m smmll cmr is smndwiched between two lmrge buses