code: def testInvalidFrequency(self):
      with self.assertRaisesRegexp(Exception, "Invalid frequency.*"):
          ninjatraderfeed.Feed(bar.Frequency.WEEK)
  
file_path: pyalgotrade/testcases/ninjatraderfeed_test.py
imports: import datetime
  from .None import common
  from .None import barfeed_test
  from .None import feed_test
  from pyalgotrade.barfeed import ninjatraderfeed
  from pyalgotrade import marketsession
  from pyalgotrade import bar
  from pyalgotrade.utils import dt
label_desc: Use image node_id 9 for calling the NinjaTraderTestCase obj's underlying member method code with example usage: obj.testInvalidFrequency() without return types