code: def verify_login(request):
      
      verifier = request.registry['persona.verifier']
      try:
          data = verifier.verify(request.POST['assertion'])
      except (ValueError, browserid.errors.TrustError) as e:
          logger.info('Failed persona login: %s (%s)', e, type(e).__name__)
          raise HTTPBadRequest('Invalid assertion')
      return data['email']
docs: Verifies the assertion and the csrf token in the given request.
  
      Returns the email of the user if everything is valid, otherwise raises
      a HTTPBadRequest