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.
Input: Sentence: 'red paint lines the walls behind an apple with a knife in it to give the illusion of blood'. Reverse all words of length '3' in the given sentence.

der paint lines eht walls behind an apple with a knife in it to give eht illusion of blood