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 small bird sitting on the rim of a fountain'. Reverse all words of length '7' in the given sentence.

SOLUTION: a small bird gnittis on the rim of a fountain

PROBLEM: Sentence: 'the three trains are stopped on the railroad tracks'. Reverse all words of length '6' in the given sentence.

SOLUTION: the three sniart are stopped on the railroad skcart

PROBLEM: Sentence: 'two signal lights displaying the red stop light'. Reverse all words of length '5' in the given sentence.

SOLUTION:
two signal lights displaying the red stop thgil