text: import pytest
  import pymasapi.client as client
  
  
  class Test_Credit_Card:
      def setup_class(cls):
          cls.c = client.Client()
  
      def teardown_method(cls):
          cls.c = None
  
      @pytest.mark.parametrize("period,limit", [("m", 5), ("y", 5)])
      def test_credit_card(cls, period, limit):
          ''' testing monthly/annual SGX-ST stats '''
          data = cls.c.sgxst(period, limit)
          assert data is not None, "data should not be None"
  