def qualified_relation_object(self, x):
    """Get the main object of x, if x is a CVT-node-like frame."""
    if isinstance(x['is'], (sling.Frame, numbers.Number)):
      return x['is']
    else:
      return None
Get the main object of x, if x is a CVT-node-like frame.
language/templama/sling2facts.py