Do you happen to know the word "darify" ?

At the age of sixty, old sight imposed me another challengin task while I was reading the comment by the reviewer printed with a font size 8 or so on the PDF. It said "I think this sentence may need to be darified". What? What do I need to "darify"? Instead, what "darify" means, in the first place? I tried to look it up in the dictionary in vain. Is the reviewer familiar with William Shakespeare, not with drug approval ? No way. It did not take much time before I found what was needed to be clarified.

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