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: 'a family climbing up the side of a snow covered mountain with ski equipment'. Reverse all words of length '4' in the given sentence.

a family climbing up the edis of a wons covered mountain htiw ski equipment