code: def verify!
        if signature.missing? && assertion.signature.missing?
          raise Samlr::SignatureError.new("Neither response nor assertion signed with a certificate")
        end
  
        signature.verify! unless signature.missing?
        assertion.verify!
  
        true
      end
docs: The verification process assumes that all signatures are enveloped. Since this process
   is destructive the document needs to verify itself first, and then any signed assertions