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.

Example Input: Sentence: 'a small white dog with a hat on his rear end'. Reverse all words of length '3' in the given sentence.
Example Output: a small white god with a tah on sih rear dne

Example Input: Sentence: 'a group of people riding in a black raft'. Reverse all words of length '1' in the given sentence.
Example Output: a group of people riding in a black raft

Example Input: Sentence: 'a little dog dressed up in pink a a black top hat looks up at the camera'. Reverse all words of length '6' in the given sentence.
Example Output:
a elttil dog dressed up in pink a a black top hat looks up at the aremac