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: 'there is a group of people standing on the beach'. Reverse all words of length '8' in the given sentence.

SOLUTION: there is a group of people gnidnats on the beach

PROBLEM: Sentence: 'a crowd is surrounding a large clock tower lit up at night'. Reverse all words of length '3' in the given sentence.

SOLUTION:
a crowd is surrounding a large clock tower til up at night