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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def of(cls, *documents: BioCDocument):
 """ Returns a collection documents """

        if len(documents) <= 0:
            raise ValueError("There has to be at least one document.")
        c = BioCCollection()
        for document in documents:
            if document is None:
                raise ValueError('Document is None')
            c.add_document(document)
        return c