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

Ex Input:
Sentence: 'a person with a cell phone standing next to a train'. Replace the letter 's' with 't' in the sentence.

Ex Output:
a perton with a cell phone ttanding next to a train

Ex Input:
Sentence: 'a child holding a tv remote like a phone'. Replace the letter 'i' with 'b' in the sentence.

Ex Output:
a chbld holdbng a tv remote lbke a phone

Ex Input:
Sentence: 'this is a cute dog sticking his head out of the window of a red car'. Replace the letter 'e' with 'z' in the sentence.

Ex Output:
this is a cutz dog sticking his hzad out of thz window of a rzd car