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: 'one zebra stands guard while the other eats on the savannah'. Reverse all words of length '3' in the given sentence.

eno zebra stands guard while eht other eats on eht savannah