def any_present?(*keys)
      keys.each do |key|
        return true if self.send(key).present?
      end
      return false
    end
def any_present?(*keys)
      keys.each do |key|
        return true if self.send(key).present?
      end
      return false
    end
convenience method that returns true if any of the keys
 are #present?  eg
 item.any_present?(:source_title, :authors) === item.source_title.present? || item.authors.present?

 note present? is false for nil, empty strings, and empty arrays.