TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a bird in a tree looking up at branches'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'a glass a rope and a pair of scissors'. Find frequency of the letter 's'

SOLUTION: 6

PROBLEM: Sentence: 'a couple of men standing by a sign with frisbees'. Find frequency of the letter 'b'

SOLUTION:
2