TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a green bus driving in a street filled with heavy traffic'. Find frequency of the letter 'v'

SOLUTION: 2

PROBLEM: Sentence: 'party cakes in plastic containers, with a cake with a plastic santa claus and reindeer on top'. Find frequency of the letter 's'

SOLUTION: 6

PROBLEM: Sentence: 'a tennis player wearing a t-shirt and a headband swings a tennis racket'. Find frequency of the letter 'h'

SOLUTION:
2