TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'two kids sitting on a  child's bed and smiling'. Replace the letter 't' with 's' in the sentence.

SOLUTION: swo kids sissing on a  child's bed and smiling

PROBLEM: Sentence: 'a train traveling through a dark tunnel next to green brush.'. Replace the letter 'r' with 'e' in the sentence.

SOLUTION: a teain teaveling theough a daek tunnel next to geeen beush.

PROBLEM: Sentence: 'a person that is walking with a umbrella'. Replace the letter 'w' with 'o' in the sentence.

SOLUTION:
a person that is oalking oith a umbrella