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

Example Input: Sentence: 'a woman standing in front of a bear in an enclosure'. Replace the letter 'e' with 'r' in the sentence.
Example Output: a woman standing in front of a brar in an rnclosurr

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 tidy desk is covered with apple products and pamphlets'. Replace the letter 'd' with 'z' in the sentence.
Example Output:
a tizy zesk is coverez with apple prozucts anz pamphlets