TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a view from a bathroom shows an open door'. Find frequency of the letter 'o'

SOLUTION: 7

PROBLEM: Sentence: 'a train on a train track going through a bunch of trees'. Find frequency of the letter 'u'

SOLUTION: 2

PROBLEM: Sentence: 'a cleaned and sanitized toilet with paper across the seat'. Find frequency of the letter 't'

SOLUTION:
6