def load!(id)
      doc = load(id)
      if id.is_a?(Array)
        missing_docs = id - doc.map(&:id)
      end
      raise(CouchPotato::NotFound, missing_docs.try(:join, ', ')) if doc.nil? || missing_docs.try(:any?)
      doc
    end
def load!(id)
      doc = load(id)
      if id.is_a?(Array)
        missing_docs = id - doc.map(&:id)
      end
      raise(CouchPotato::NotFound, missing_docs.try(:join, ', ')) if doc.nil? || missing_docs.try(:any?)
      doc
    end
loads one or more documents by its id(s)
 behaves like #load except it raises a CouchPotato::NotFound if any of the documents could not be found