TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a group of tennis players on a tennis court'. Find frequency of the letter 'o'

SOLUTION: 4

PROBLEM: Sentence: 'a giraffe sticking it's tongue out near a window'. Find frequency of the letter 'a'

SOLUTION: 4

PROBLEM: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'

SOLUTION:
4