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: 'the bicyclist is sitting on the back of the decorative bench to check her phone'. Reverse all words of length '3' in the given sentence.

eht bicyclist is sitting on eht back of eht decorative bench to check reh phone