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

Example Input: Sentence: 'an elephant in chains converses with a smaller elephant who is not wearing chains'. Replace the letter 'i' with 'm' in the sentence.
Example Output: an elephant mn chamns converses wmth a smaller elephant who ms not wearmng chamns

Example Input: Sentence: 'a black cat is sniffing a glass bottle'. Replace the letter 'c' with 'f' in the sentence.
Example Output: a blafk fat is sniffing a glass bottle

Example Input: Sentence: 'this is a picture telling people what vehicles are allowed on this street'. Replace the letter 'l' with 'u' in the sentence.
Example Output:
this is a picture teuuing peopue what vehicues are auuowed on this street