Give a possible regular expression that generates the language L consisting of all words in which

all words

either contain no as at all, or

when there are as$,$ they occur in clumps of three or more as$,$ and

when there are as$,$ there are an even number of such clumps of as$.$

For instance, words such as b$,$ bbbbbaaaabaaaaabbb and aaabbbaaaaaabaaabaaab are words

in this language, and words such as aaaa and aaabaa are not words in the language.