TASK DEFINITION: In this task, you need to reverse all words of a given length in the sentence. The number of letters in a word determine its length. For example, the length of the word "apple" is 5.
PROBLEM: Sentence: 'a couple of trains are sitting on some tracks'. Reverse all words of length '2' in the given sentence.

SOLUTION: a couple fo trains are sitting no some tracks

PROBLEM: Sentence: 'man extending arm with three bananas crosswise on it'. Reverse all words of length '4' in the given sentence.

SOLUTION: man extending arm htiw three bananas crosswise on it

PROBLEM: Sentence: 'a stop and a street sign on a pole'. Reverse all words of length '1' in the given sentence.

SOLUTION:
a stop and a street sign on a pole