TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a person that is sitting under an umbrella'. Replace the letter 'a' with 'l' in the sentence.

SOLUTION: l person thlt is sitting under ln umbrelll

PROBLEM: Sentence: 'red helicopter with landing wheels flying in the sky'. Replace the letter 'h' with 'y' in the sentence.

SOLUTION: red yelicopter wity landing wyeels flying in tye sky

PROBLEM: Sentence: 'a lady holding a lite cake while a man holding a baby looks on'. Replace the letter 'b' with 'v' in the sentence.

SOLUTION:
a lady holding a lite cake while a man holding a vavy looks on