code: def markers_pass(self, req, extras=None):
          
          extra_evals = (
              req.marker.evaluate({'extra': extra})
              for extra in self.get(req, ()) + (extras or (None,))
          )
          return not req.marker or any(extra_evals)
docs: Evaluate markers for req against each extra that
          demanded it.
  
          Return False if the req has a marker and fails
          evaluation. Otherwise, return True.